[Bug]: audio.svg missing for mp3 files in activity stream

⚠️ This issue respects the following points: ⚠️

• This is a bug, not a question or a configuration/webserver/proxy issue.
• This issue is not already reported on Github OR Nextcloud Community Forum (I've searched it).
• Nextcloud Server is up to date. See Maintenance and Release Schedule for supported versions.
• I agree to follow Nextcloud's Code of Conduct.

Bug description

When uploading a mp3 file with the ending .mp3 the audio icon is missing in the activity stream. This issue is present at least since NC 29.

Steps to reproduce

1. Upload a file with .mp3 ending (lower case)
2. Check the Activity Stream

Expected behavior

mp3 icon should show up

Actual behaviour
A missing image icon is displayed instead

Nextcloud Server version

31

Operating system

Debian/Ubuntu

PHP engine version

PHP 8.3

Web server

Apache (supported)

Database engine version

MariaDB

Is this bug present after an update or on a fresh install?

None

Are you using the Nextcloud Server Encryption module?

Encryption is Enabled

What user-backends are you using?

• Default user-backend (database)
• LDAP/ Active Directory
• SSO - SAML
• Other

Configuration report

{    "system": {        "instanceid": "***REMOVED SENSITIVE VALUE***",        "passwordsalt": "***REMOVED SENSITIVE VALUE***",        "secret": "***REMOVED SENSITIVE VALUE***",        "trusted_domains": [            "cloud.geistigewelt.tv",            "www.geistigewelt.tv",            "www.vollendungderseele.com"        ],        "datadirectory": "***REMOVED SENSITIVE VALUE***",        "dbtype": "mysql",        "version": "31.0.5.1",        "overwrite.cli.url": "https:\/\/cloud.geistigewelt.tv",        "dbname": "***REMOVED SENSITIVE VALUE***",        "dbhost": "***REMOVED SENSITIVE VALUE***",        "dbport": "",        "dbtableprefix": "oc_",        "mysql.utf8mb4": true,        "dbuser": "***REMOVED SENSITIVE VALUE***",        "dbpassword": "***REMOVED SENSITIVE VALUE***",        "logtimezone": "UTC",        "installed": true,        "mail_smtpmode": "smtp",        "mail_sendmailmode": "smtp",        "mail_from_address": "***REMOVED SENSITIVE VALUE***",        "mail_domain": "***REMOVED SENSITIVE VALUE***",        "default_language": "de",        "force_language": "de",        "default_locale": "de_DE",        "default_phone_region": "DE",        "filelocking.enabled": true,        "memcache.local": "\\OC\\Memcache\\APCu",        "memcache.distributed": "\\OC\\Memcache\\Redis",        "cache_ttl": 600,        "maintenance": false,        "maintenance_window_start": 5,        "updater.release.channel": "stable",        "theme": "",        "loglevel": 3,        "mail_smtpsecure": "tls",        "mail_smtphost": "***REMOVED SENSITIVE VALUE***",        "mail_smtpport": "25",        "app_install_overwrite": [            "documentserver_community",            "cookbook",            "richdocumentscode",            "passwords",            "richdocuments",            "theming_customcss",            "event_update_notification",            "occweb",            "files_rightclick",            "appointments"        ],        "encryption.key_storage_migrated": false,        "memcache.locking": "\\OC\\Memcache\\Redis",        "redis": {            "host": "***REMOVED SENSITIVE VALUE***",            "port": 6379,            "timeout": 0,            "password": "***REMOVED SENSITIVE VALUE***"        },        "defaultapp": ""    }}

List of activated Apps

Nextcloud Signing status

Nextcloud Logs

Additional info

No response

Start by reproducing the issue in the Activity Stream with a lowercase .mp3 upload, then trace the missing image reference for that activity entry. Done means the expected audio icon displays instead of a missing-image placeholder.