Public room list does not return results when searching for room title with uppercase umlaut

This issue has been migrated from [#15419](https://github.com/matrix-org/synapse/issues/15419).

---

### Description

When searching for a room in the public room directory via Element, it will not appear when entering the room title. Manually scrolling down without entering any search terms will show the room, however. From my limited testing, this only seems to affect rooms with uppercase umlaut characters (`ÄÖÜ`). Room titles with said characters anywhere else will be found as expected, see examples below.

### Steps to reproduce

In Element
- create public room with local address #testraum:example.org and title Apföl
- publish room to the public
- search for room in public room directory

Results are the same for requests sent to either main process and generic_workers. Examples with curl:

Room title is `Apföl`
```
# curl -s -H 'Authorization: Bearer xxx' -d '{ "filter": { "generic_search_term": "Apföl", "room_types": null } }' localhost:8008/_matrix/client/v3/publicRooms | jq '.chunk | .[]'
{
"room_id": "!pRruVxBDfrjmlCdIyF:example.org",
"name": "Apföl",
"topic": "Thema\n",
"canonical_alias": "#testraum:example.org",
"num_joined_members": 3,
"world_readable": false,
"guest_can_join": true,
"join_rule": "public"
}
```
Then change the room title to `Öach`
```
# curl -s -H 'Authorization: Bearer xxx' -d '{ "filter": { "generic_search_term": "Öach", "room_types": null } }' localhost:8008/_matrix/client/v3/publicRooms
{
"chunk": [],
"total_room_count_estimate": 30
}
```
However, removing the `generic_search_term` will give a hit
```
# curl -s -H 'Authorization: Bearer xxx' -d '{ "filter": { "generic_search_term": "", "room_types": null } }' localhost:8008/_matrix/client/v3/publicRooms | jq '.chunk | .[] | select(.name == "Öach")'
{
"room_id": "!pRruVxBDfrjmlCdIyF:example.org",
"name": "Öach",
"topic": "Thema\n",
"canonical_alias": "#testraum:example.org",
"num_joined_members": 3,
"world_readable": false,
"guest_can_join": true,
"join_rule": "public"
}
```

### Homeserver

Local test install

### Synapse Version

1.80.0

### Installation Method

Debian packages from packages.matrix.org

### Database

PostgresSQL (13.9-0+deb11u1, same host), fresh install

### Workers

Multiple workers

### Platform

VM, Debian 11

### Configuration

_No response_

### Relevant log output

```shell
# room title = Apföl, generic_search_term = "Apföl"
2023-04-11 18:35:04,955 - synapse.access.http.8008 - 415 - DEBUG - POST-121 - ::1 - 8008 - Received request: POST /_matrix/client/v3/publicRooms
2023-04-11 18:35:04,959 - synapse.storage.txn - 710 - DEBUG - POST-121 - [TXN START] {get_user_by_access_token-95}
2023-04-11 18:35:04,959 - synapse.storage.SQL - 426 - DEBUG - POST-121 - [SQL] {get_user_by_access_token-95} SELECT users.name as user_id, users.is_guest, users.shadow_banne
d, access_tokens.id as token_id, access_tokens.device_id, access_tokens.valid_until_ms, access_tokens.user_id as token_owner, access_tokens.used as token_used FROM users INN
ER JOIN access_tokens on users.name = COALESCE(puppets_user_id, access_tokens.user_id) WHERE token = ?
2023-04-11 18:35:04,959 - synapse.storage.SQL - 431 - DEBUG - POST-121 - [SQL values] {get_user_by_access_token-95} ('xxx',)
2023-04-11 18:35:04,960 - synapse.storage.SQL - 452 - DEBUG - POST-121 - [SQL time] {get_user_by_access_token-95} 0.000929 sec
2023-04-11 18:35:04,960 - synapse.storage.txn - 814 - DEBUG - POST-121 - [TXN END] {get_user_by_access_token-95} 0.001381 sec
2023-04-11 18:35:04,961 - synapse.storage.txn - 710 - DEBUG - POST-121 - [TXN START] {mark_access_token_as_used-96}
2023-04-11 18:35:04,961 - synapse.storage.SQL - 426 - DEBUG - POST-121 - [SQL] {mark_access_token_as_used-96} UPDATE access_tokens SET used = ? WHERE id = ?
2023-04-11 18:35:04,961 - synapse.storage.SQL - 431 - DEBUG - POST-121 - [SQL values] {mark_access_token_as_used-96} [True, 4539]
2023-04-11 18:35:04,962 - synapse.storage.SQL - 452 - DEBUG - POST-121 - [SQL time] {mark_access_token_as_used-96} 0.000772 sec
2023-04-11 18:35:04,962 - synapse.storage.txn - 814 - DEBUG - POST-121 - [TXN END] {mark_access_token_as_used-96} 0.001181 sec
2023-04-11 18:35:04,963 - synapse.handlers.room_list - 90 - INFO - POST-121 - Getting public room list: limit=100, since=None, search=True, network=ThirdPartyInstanceID(apps
ervice_id=None, network_id=None)
2023-04-11 18:35:04,963 - synapse.handlers.room_list - 101 - INFO - POST-121 - Bypassing cache as search request.
2023-04-11 18:35:04,963 - synapse.storage.txn - 710 - DEBUG - POST-121 - [TXN START] {get_largest_public_rooms-97}
2023-04-11 18:35:04,963 - synapse.storage.SQL - 426 - DEBUG - POST-121 - [SQL] {get_largest_public_rooms-97} SELECT room_id, name, topic, canonical_alias, joined_members, av
atar, history_visibility, guest_access, join_rules, room_type FROM ( SELECT room_id FROM rooms WHERE is_public ) published INNER JOIN room_stats_state USING (room_id) INNER
JOIN room_stats_current USING (room_id) WHERE ( join_rules = 'public' OR join_rules = 'knock' OR join_rules = 'knock_restricted' OR history_visibility = 'world_readable' ) A
ND joined_members > 0 AND ( LOWER(name) LIKE ? OR LOWER(topic) LIKE ? OR LOWER(canonical_alias) LIKE ? ) ORDER BY joined_members DESC, room_id DESC LIMIT ?
2023-04-11 18:35:04,963 - synapse.storage.SQL - 431 - DEBUG - POST-121 - [SQL values] {get_largest_public_rooms-97} ['%apföl%', '%apföl%', '%apföl%', 101]
2023-04-11 18:35:04,964 - synapse.storage.txn - 710 - DEBUG - replication-USER_IP-55 - [TXN START] {get_user_by_id-98}
2023-04-11 18:35:04,964 - synapse.storage.SQL - 426 - DEBUG - replication-USER_IP-55 - [SQL] {get_user_by_id-98} SELECT name, password_hash, is_guest, admin, consent_version, consent_ts, consent_server_notice_sent, appservice_id, creation_ts, user_type, deactivated, COALESCE(shadow_banned, FALSE) AS shadow_banned, COALESCE(approved, TRUE) AS approved FROM users WHERE name = ?
2023-04-11 18:35:04,964 - synapse.storage.SQL - 431 - DEBUG - replication-USER_IP-55 - [SQL values] {get_user_by_id-98} ('@testmensch_bob:example.org',)
2023-04-11 18:35:04,965 - synapse.storage.SQL - 452 - DEBUG - replication-USER_IP-55 - [SQL time] {get_user_by_id-98} 0.000373 sec
2023-04-11 18:35:04,965 - synapse.storage.txn - 814 - DEBUG - replication-USER_IP-55 - [TXN END] {get_user_by_id-98} 0.000890 sec
2023-04-11 18:35:04,965 - synapse.storage.SQL - 452 - DEBUG - POST-121 - [SQL time] {get_largest_public_rooms-97} 0.002291 sec
2023-04-11 18:35:04,966 - synapse.storage.txn - 814 - DEBUG - POST-121 - [TXN END] {get_largest_public_rooms-97} 0.002620 sec
2023-04-11 18:35:04,966 - synapse.storage.txn - 710 - DEBUG - POST-121 - [TXN START] {count_public_rooms-99}
2023-04-11 18:35:04,966 - synapse.storage.SQL - 426 - DEBUG - POST-121 - [SQL] {count_public_rooms-99} SELECT COUNT(*) FROM ( SELECT room_id FROM rooms WHERE is_public ) published INNER JOIN room_stats_state USING (room_id) INNER JOIN room_stats_current USING (room_id) WHERE ( join_rules = 'public' OR join_rules = 'knock' OR join_rules = 'knock_restricted' OR history_visibility = 'world_readable' ) AND joined_members > 0
2023-04-11 18:35:04,966 - synapse.storage.SQL - 431 - DEBUG - POST-121 - [SQL values] {count_public_rooms-99} []
2023-04-11 18:35:04,968 - synapse.storage.SQL - 452 - DEBUG - POST-121 - [SQL time] {count_public_rooms-99} 0.002087 sec
2023-04-11 18:35:04,969 - synapse.storage.txn - 814 - DEBUG - POST-121 - [TXN END] {count_public_rooms-99} 0.002664 sec
2023-04-11 18:35:04,970 - synapse.access.http.8008 - 460 - INFO - POST-121 - ::1 - 8008 - {@testmensch_bob:example.org} Processed request: 0.015sec/0.000sec (0.003sec, 0.001sec) (0.004sec/0.008sec/4) 257B 200 "POST /_matrix/client/v3/publicRooms HTTP/1.1" "curl/7.74.0" [0 dbevts]

# room title = Öach, generic_search_term = "Öach"
2023-04-11 18:47:46,742 - synapse.access.http.8008 - 415 - DEBUG - POST-356 - ::1 - 8008 - Received request: POST /_matrix/client/v3/publicRooms
2023-04-11 18:47:46,743 - synapse.storage.txn - 710 - DEBUG - POST-356 - [TXN START] {get_user_by_access_token-181}
2023-04-11 18:47:46,743 - synapse.storage.SQL - 426 - DEBUG - POST-356 - [SQL] {get_user_by_access_token-181} SELECT users.name as user_id, users.is_guest, users.shadow_bann
ed, access_tokens.id as token_id, access_tokens.device_id, access_tokens.valid_until_ms, access_tokens.user_id as token_owner, access_tokens.used as token_used FROM users IN
NER JOIN access_tokens on users.name = COALESCE(puppets_user_id, access_tokens.user_id) WHERE token = ?
2023-04-11 18:47:46,743 - synapse.storage.SQL - 431 - DEBUG - POST-356 - [SQL values] {get_user_by_access_token-181} ('xxx',)
2023-04-11 18:47:46,745 - synapse.storage.SQL - 452 - DEBUG - POST-356 - [SQL time] {get_user_by_access_token-181} 0.001587 sec
2023-04-11 18:47:46,745 - synapse.storage.txn - 814 - DEBUG - POST-356 - [TXN END] {get_user_by_access_token-181} 0.002667 sec
2023-04-11 18:47:46,747 - synapse.storage.txn - 710 - DEBUG - POST-356 - [TXN START] {mark_access_token_as_used-182}
2023-04-11 18:47:46,747 - synapse.storage.SQL - 426 - DEBUG - POST-356 - [SQL] {mark_access_token_as_used-182} UPDATE access_tokens SET used = ? WHERE id = ?
2023-04-11 18:47:46,747 - synapse.storage.SQL - 431 - DEBUG - POST-356 - [SQL values] {mark_access_token_as_used-182} [True, 4539]
2023-04-11 18:47:46,748 - synapse.storage.SQL - 452 - DEBUG - POST-356 - [SQL time] {mark_access_token_as_used-182} 0.000796 sec
2023-04-11 18:47:46,748 - synapse.storage.txn - 814 - DEBUG - POST-356 - [TXN END] {mark_access_token_as_used-182} 0.001326 sec
2023-04-11 18:47:46,749 - synapse.handlers.room_list - 90 - INFO - POST-356 - Getting public room list: limit=100, since=None, search=True, network=ThirdPartyInstanceID(appservice_id=None, network_id=None)
2023-04-11 18:47:46,749 - synapse.handlers.room_list - 101 - INFO - POST-356 - Bypassing cache as search request.
2023-04-11 18:47:46,750 - synapse.storage.txn - 710 - DEBUG - POST-356 - [TXN START] {get_largest_public_rooms-183}
2023-04-11 18:47:46,750 - synapse.storage.SQL - 426 - DEBUG - POST-356 - [SQL] {get_largest_public_rooms-183} SELECT room_id, name, topic, canonical_alias, joined_members, avatar, history_visibility, guest_access, join_rules, room_type FROM ( SELECT room_id FROM rooms WHERE is_public ) published INNER JOIN room_stats_state USING (room_id) INNER JOIN room_stats_current USING (room_id) WHERE ( join_rules = 'public' OR join_rules = 'knock' OR join_rules = 'knock_restricted' OR history_visibility = 'world_readable' ) AND joined_members > 0 AND ( LOWER(name) LIKE ? OR LOWER(topic) LIKE ? OR LOWER(canonical_alias) LIKE ? ) ORDER BY joined_members DESC, room_id DESC LIMIT ?
2023-04-11 18:47:46,750 - synapse.storage.SQL - 431 - DEBUG - POST-356 - [SQL values] {get_largest_public_rooms-183} ['%öach%', '%öach%', '%öach%', 101]
2023-04-11 18:47:46,752 - synapse.storage.txn - 710 - DEBUG - replication-USER_IP-28 - [TXN START] {get_user_by_id-184}
2023-04-11 18:47:46,752 - synapse.storage.SQL - 426 - DEBUG - replication-USER_IP-28 - [SQL] {get_user_by_id-184} SELECT name, password_hash, is_guest, admin, consent_version, consent_ts, consent_server_notice_sent, appservice_id, creation_ts, user_type, deactivated, COALESCE(shadow_banned, FALSE) AS shadow_banned, COALESCE(approved, TRUE) AS approved FROM users WHERE name = ?
2023-04-11 18:47:46,752 - synapse.storage.SQL - 431 - DEBUG - replication-USER_IP-28 - [SQL values] {get_user_by_id-184} ('@testmensch_bob:example.org',)
2023-04-11 18:47:46,752 - synapse.storage.SQL - 452 - DEBUG - replication-USER_IP-28 - [SQL time] {get_user_by_id-184} 0.000376 sec
2023-04-11 18:47:46,753 - synapse.storage.txn - 814 - DEBUG - replication-USER_IP-28 - [TXN END] {get_user_by_id-184} 0.000987 sec
2023-04-11 18:47:46,756 - synapse.storage.SQL - 452 - DEBUG - POST-356 - [SQL time] {get_largest_public_rooms-183} 0.005281 sec
2023-04-11 18:47:46,756 - synapse.storage.txn - 814 - DEBUG - POST-356 - [TXN END] {get_largest_public_rooms-183} 0.005886 sec
2023-04-11 18:47:46,757 - synapse.storage.txn - 710 - DEBUG - POST-356 - [TXN START] {count_public_rooms-185}
2023-04-11 18:47:46,757 - synapse.storage.SQL - 426 - DEBUG - POST-356 - [SQL] {count_public_rooms-185} SELECT COUNT(*) FROM ( SELECT room_id FROM rooms WHERE is_public ) published INNER JOIN room_stats_state USING (room_id) INNER JOIN room_stats_current USING (room_id) WHERE ( join_rules = 'public' OR join_rules = 'knock' OR join_rules = 'knock_restricted' OR history_visibility = 'world_readable' ) AND joined_members > 0
2023-04-11 18:47:46,757 - synapse.storage.SQL - 431 - DEBUG - POST-356 - [SQL values] {count_public_rooms-185} []
2023-04-11 18:47:46,758 - synapse.storage.SQL - 452 - DEBUG - POST-356 - [SQL time] {count_public_rooms-185} 0.001768 sec
2023-04-11 18:47:46,759 - synapse.storage.txn - 814 - DEBUG - POST-356 - [TXN END] {count_public_rooms-185} 0.002080 sec
2023-04-11 18:47:46,760 - synapse.access.http.8008 - 460 - INFO - POST-356 - ::1 - 8008 - {@testmensch_bob:example.org} Processed request: 0.017sec/0.001sec (0.003sec, 0.001sec) (0.002sec/0.012sec/4) 43B 200 "POST /_matrix/client/v3/publicRooms HTTP/1.1" "curl/7.74.0" [0 dbevts]

# room title = Öach, generic_search_term = ""
2023-04-11 18:48:15,041 - synapse.access.http.8008 - 415 - DEBUG - POST-472 - ::1 - 8008 - Received request: POST /_matrix/client/v3/publicRooms
2023-04-11 18:48:15,042 - synapse.handlers.room_list - 90 - INFO - POST-472 - Getting public room list: limit=100, since=None, search=True, network=ThirdPartyInstanceID(appservice_id=None, network_id=None)
2023-04-11 18:48:15,042 - synapse.handlers.room_list - 101 - INFO - POST-472 - Bypassing cache as search request.
2023-04-11 18:48:15,043 - synapse.storage.txn - 710 - DEBUG - POST-472 - [TXN START] {get_largest_public_rooms-1b9}
2023-04-11 18:48:15,043 - synapse.storage.SQL - 426 - DEBUG - POST-472 - [SQL] {get_largest_public_rooms-1b9} SELECT room_id, name, topic, canonical_alias, joined_members, avatar, history_visibility, guest_access, join_rules, room_type FROM ( SELECT room_id FROM rooms WHERE is_public ) published INNER JOIN room_stats_state USING (room_id) INNER JOIN room_stats_current USING (room_id) WHERE ( join_rules = 'public' OR join_rules = 'knock' OR join_rules = 'knock_restricted' OR history_visibility = 'world_readable' ) AND joined_members > 0 ORDER BY joined_members DESC, room_id DESC LIMIT ?
2023-04-11 18:48:15,043 - synapse.storage.SQL - 431 - DEBUG - POST-472 - [SQL values] {get_largest_public_rooms-1b9} [101]
2023-04-11 18:48:15,045 - synapse.storage.SQL - 452 - DEBUG - POST-472 - [SQL time] {get_largest_public_rooms-1b9} 0.001752 sec
2023-04-11 18:48:15,045 - synapse.storage.txn - 814 - DEBUG - POST-472 - [TXN END] {get_largest_public_rooms-1b9} 0.002537 sec
2023-04-11 18:48:15,046 - synapse.storage.txn - 710 - DEBUG - POST-472 - [TXN START] {count_public_rooms-1ba}
2023-04-11 18:48:15,046 - synapse.storage.SQL - 426 - DEBUG - POST-472 - [SQL] {count_public_rooms-1ba} SELECT COUNT(*) FROM ( SELECT room_id FROM rooms WHERE is_public ) published INNER JOIN room_stats_state USING (room_id) INNER JOIN room_stats_current USING (room_id) WHERE ( join_rules = 'public' OR join_rules = 'knock' OR join_rules = 'knock_restricted' OR history_visibility = 'world_readable' ) AND joined_members > 0
2023-04-11 18:48:15,046 - synapse.storage.SQL - 431 - DEBUG - POST-472 - [SQL values] {count_public_rooms-1ba} []
2023-04-11 18:48:15,049 - synapse.storage.SQL - 452 - DEBUG - POST-472 - [SQL time] {count_public_rooms-1ba} 0.002460 sec
2023-04-11 18:48:15,049 - synapse.storage.txn - 814 - DEBUG - POST-472 - [TXN END] {count_public_rooms-1ba} 0.002995 sec
2023-04-11 18:48:15,051 - synapse.access.http.8008 - 460 - INFO - POST-472 - ::1 - 8008 - {@testmensch_bob:example.org} Processed request: 0.009sec/0.001sec (0.000sec, 0.001sec) (0.001sec/0.006sec/2) 7839B 200 "POST /_matrix/client/v3/publicRooms HTTP/1.1" "curl/7.74.0" [0 dbevts]
```

### Anything else that would be useful to know?

_No response_