Checkboxes don't get checked in rendered mode / Same Issue as #2061 again

Describe the bug
In rendered markdown view, checkboxes can be checked but after closing the card this will be lost. The next time you view the card, the checkbox will be unchecked again. This only happens when viewing through a browser, the mobile app (for Android) behaves as expected. I think issues #2061 was about the same bug, but it was closed and should be resolved with a release in late 2023.

To Reproduce
Steps to reproduce the behavior:

1. Open a deck card
2. Enter Markdown in the description, eg. "- [ ] buy apples"
3. Change to rendered markdown view
4. Check the Checkbox
5. Close the card
6. Task reading on the card will be "0/1" (Bug, should be "1/1")
7. Open the card again
8. Checkbox apears unchecked (Status should be "checked")

Expected behavior
When i click a checkbox in rendered view, this should be saved when I close the card

Screenshots
n/a

Client details:

• OS: Arch Linux
• Browser: Firefox
• Version: 126.0.1
• Device: Desktop PC

Server details

Operating system: Host is an Ubuntu Server, running the dockerized version (official image)

Web server: Nginx Proxy (for ssl)

Database: MariaDB (official image from docker hub)

PHP version: Whatever is in the official image

Nextcloud version: Nextcloud Hub 8 (29.0.0)

Login as admin user into your Nextcloud and access
http://example.com/index.php/settings/integrity/failed
paste the results here.

No errors have been found

List of activated apps:

Enabled:
  - activity: 2.21.1
  - admin_audit: 1.19.0
  - bookmarks: 14.1.1
  - breezedark: 28.0.0
  - calendar: 4.7.4
  - cloud_federation_api: 1.12.0
  - comments: 1.19.0
  - contacts: 6.0.0
  - contactsinteraction: 1.10.0
  - cookbook: 0.11.0
  - dashboard: 7.9.0
  - dav: 1.30.1
  - deck: 1.13.0
  - federatedfilesharing: 1.19.0
  - federation: 1.19.0
  - files: 2.1.0
  - files_downloadlimit: 2.0.0
  - files_external: 1.21.0
  - files_pdfviewer: 2.10.0
  - files_reminders: 1.2.0
  - files_sharing: 1.21.0
  - files_trashbin: 1.19.0
  - files_versions: 1.22.0
  - lookup_server_connector: 1.17.0
  - metadata: 0.20.0
  - notifications: 2.17.0
  - oauth2: 1.17.0
  - photos: 2.5.0
  - provisioning_api: 1.19.0
  - related_resources: 1.4.0
  - settings: 1.12.0
  - sharebymail: 1.19.0
  - spreed: 19.0.1
  - tasks: 0.16.0
  - theming: 2.4.0
  - twofactor_backupcodes: 1.18.0
  - viewer: 2.3.0
  - workflowengine: 2.11.0
Disabled:
  - bruteforcesettings: 2.9.0 (installed 2.4.0)
  - circles: 29.0.0-dev (installed 22.1.1)
  - encryption: 2.17.0
  - files_markdown: 2.4.1 (installed 2.4.1)
  - files_rightclick: 0.15.1 (installed 0.15.1)
  - files_texteditor: 2.15.1 (installed 2.15.1)
  - firstrunwizard: 2.18.0 (installed 2.13.0)
  - logreader: 2.14.0 (installed 2.9.0)
  - nextcloud_announcements: 1.18.0 (installed 1.13.0)
  - notes: 4.10.0 (installed 4.10.0)
  - password_policy: 1.19.0 (installed 1.14.0)
  - privacy: 1.13.0 (installed 1.8.0)
  - recommendations: 2.1.0 (installed 1.3.0)
  - richdocuments: 8.4.2 (installed 8.4.2)
  - serverinfo: 1.19.0 (installed 1.14.0)
  - support: 1.12.0 (installed 1.7.0)
  - survey_client: 1.17.0 (installed 1.12.0)
  - suspicious_login: 7.0.0
  - systemtags: 1.19.0 (installed 1.19.0)
  - text: 3.10.0 (installed 3.5.1)
  - twofactor_totp: 11.0.0-dev
  - updatenotification: 1.19.1 (installed 1.14.0)
  - user_ldap: 1.20.0
  - user_status: 1.9.0 (installed 1.4.0)
  - weather_status: 1.9.0 (installed 1.4.0)

Nextcloud configuration:

{
    "system": {
        "htaccess.RewriteBase": "\/",
        "memcache.local": "\\OC\\Memcache\\APCu",
        "apps_paths": [
            {
                "path": "\/var\/www\/html\/apps",
                "url": "\/apps",
                "writable": false
            },
            {
                "path": "\/var\/www\/html\/custom_apps",
                "url": "\/custom_apps",
                "writable": true
            }
        ],
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "192.168.55.10",
            "nextcloud.as55.lan",
            "server.as55.lan"
        ],
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "mysql",
        "version": "29.0.0.19",
        "overwrite.cli.url": "https:\/\/nextcloud.as55.lan",
        "overwriteprotocol": "https",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbport": "",
        "dbtableprefix": "oc_",
        "mysql.utf8mb4": true,
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "installed": true,
        "app_install_overwrite": [
            "whiteboard",
            "occweb",
            "bookmarks",
            "bookmarks_fulltextsearch",
            "breezedark",
            "news",
            "metadata",
            "files_rightclick",
            "files_markdown",
            "tasks",
            "files_texteditor"
        ],
        "theme": "",
        "loglevel": 0,
        "maintenance": false,
        "maintenance_window_start": 1,
        "memcache.distributed": "\\OC\\Memcache\\Redis",
        "memcache.locking": "\\OC\\Memcache\\Redis",
        "redis": {
            "host": "***REMOVED SENSITIVE VALUE***",
            "password": "***REMOVED SENSITIVE VALUE***",
            "port": 6379
        }
    }
}

Are you using an external user-backend, if yes which one: LDAP/ActiveDirectory/Webdav/...

Nope.

I did not find any log entries related to the deck app at al. Other logdata contains usernames and other personal data. I can share this via mail if really necessary.

Start by reproducing the checkbox behavior in a browser using a Deck card with rendered Markdown, then trace the browser-side save and reload path and compare it with the working Android behavior. Done means a checked task remains checked after closing and reopening the card, with the card showing 1/1.