[Bug]: Nextcloud 33 - Comment mentions fail to trigger notifications or appear in Activity app

[qtohouse]

⚠️ 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

After updating to Nextcloud 33 via the manual Nextcloud AIO override (testing the Hub 26 Winter release), comment mentions (@username) are completely broken.

When a user is tagged in a comment on a file or folder:

The tagged user receives no instant notification (bell icon).

The mention does not generate an entry in the Activity app feed.

No email notification is dispatched.

Standard file activities (like file creation/modification) still appear in the Activity feed, but the specific hooks for comment mentions seem to be dropping or failing to resolve the user ID.

Steps to reproduce

1.Spin up Nextcloud 33 (via AIO PR #7523 override).
2. Have User A open the details panel for any file or folder.
3. Under the Comments tab, type a comment and tag User B (e.g., @userb please review this).
4. Log in as User B. Observe that the notification bell is empty and the Activity feed shows no record of the mention.

Expected behavior

When a user is mentioned in a comment using the @ symbol, the system should immediately dispatch a web notification to the target user, log the mention in the target user's Activity feed, and trigger an email notification (if configured).

Nextcloud Server version

33

Operating system

Debian/Ubuntu

PHP engine version

PHP 8.3

Web server

Apache (supported)

Database engine version

PostgreSQL

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

Upgraded to a MAJOR version (ex. 31 to 32)

Are you using the Nextcloud Server Encryption module?

None

What user-backends are you using?

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

Configuration report

{
    "system": {
        "php.memory_limit": "4096M",
        "one-click-instance": true,
        "one-click-instance.user-limit": 100,
        "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
            }
        ],
        "check_data_directory_permissions": false,
        "memcache.distributed": "\\OC\\Memcache\\Redis",
        "memcache.locking": "\\OC\\Memcache\\Redis",
        "redis": {
            "host": "***REMOVED SENSITIVE VALUE***",
            "password": "***REMOVED SENSITIVE VALUE***",
            "port": 6379
        },
        "overwritehost": "files.qto.company",
        "overwriteprotocol": "https",
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "localhost",
            "files.qto.company"
        ],
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "pgsql",
        "version": "33.0.2.2",
        "overwrite.cli.url": "https:\/\/files.qto.company\/",
        "push_server_url": "https:\/\/files.qto.company\/push\/",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbport": "",
        "dbtableprefix": "oc_",
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "installed": true,
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "maintenance": false,
        "updatedirectory": "\/nc-updater",
        "loglevel": 2,
        "app_install_overwrite": [
            "nextcloud-aio",
            "fulltextsearch_elasticsearch"
        ],
        "log_type": "file",
        "logfile": "\/var\/www\/html\/data\/nextcloud.log",
        "log_rotate_size": 10485760,
        "log.condition": {
            "apps": [
                "admin_audit"
            ]
        },
        "preview_max_x": 2048,
        "preview_max_y": 2048,
        "jpeg_quality": 60,
        "enabledPreviewProviders": {
            "0": "OC\\Preview\\Imaginary",
            "1": "OC\\Preview\\MarkDown",
            "2": "OC\\Preview\\MP3",
            "3": "OC\\Preview\\TXT",
            "4": "OC\\Preview\\OpenDocument",
            "5": "OC\\Preview\\Movie",
            "6": "OC\\Preview\\Krita",
            "7": "OC\\Preview\\Imaginary",
            "8": "OC\\Preview\\ImaginaryPDF",
            "9": "OC\\Preview\\HEIC",
            "10": "OC\\Preview\\TIFF",
            "23": "OC\\Preview\\ImaginaryPDF"
        },
        "enable_previews": true,
        "upgrade.disable-web": true,
        "mail_smtpmode": "sendmail",
        "trashbin_retention_obligation": "auto, 30",
        "versions_retention_obligation": "auto, 30",
        "activity_expire_days": 30,
        "simpleSignUpLink.shown": false,
        "share_folder": "\/Shared",
        "one-click-instance.link": "https:\/\/nextcloud.com\/all-in-one\/",
        "upgrade.cli-upgrade-link": "https:\/\/github.com\/nextcloud\/all-in-one\/discussions\/2726",
        "maintenance_window_start": 100,
        "allow_local_remote_servers": true,
        "davstorage.request_timeout": 36000,
        "htaccess.RewriteBase": "\/",
        "dbpersistent": false,
        "auth.bruteforce.protection.enabled": true,
        "ratelimit.protection.enabled": true,
        "files_external_allow_create_new_local": false,
        "trusted_proxies": "***REMOVED SENSITIVE VALUE***",
        "preview_imaginary_url": "***REMOVED SENSITIVE VALUE***",
        "preview_imaginary_key": "***REMOVED SENSITIVE VALUE***",
        "defaultapp": "",
        "ldapProviderFactory": "OCA\\User_LDAP\\LDAPProviderFactory",
        "default_phone_region": "PK",
        "memories.db.triggers.fcu": true,
        "memories.exiftool": "\/var\/www\/html\/custom_apps\/memories\/bin-ext\/exiftool-amd64-musl",
        "memories.vod.path": "\/var\/www\/html\/custom_apps\/memories\/bin-ext\/go-vod-amd64",
        "memories.vod.ffmpeg": "\/usr\/bin\/ffmpeg",
        "memories.vod.ffprobe": "\/usr\/bin\/ffprobe",
        "forbidden_filename_characters": [
            "<",
            ">",
            ":",
            "\"",
            "|",
            "?",
            "*",
            "\\",
            "\/"
        ],
        "forbidden_filename_extensions": [
            " ",
            ".",
            ".filepart",
            ".part"
        ],
        "documentation_url.server_logs": "https:\/\/github.com\/nextcloud\/all-in-one\/discussions\/5425",
        "updater.release.channel": "stable",
        "mail_sendmailmode": "smtp",
        "data-fingerprint": "771ea58faf704777f37864ee23f53562",
        "updatechecker": true,
        "forbidden_filename_basenames": [
            "con",
            "prn",
            "aux",
            "nul",
            "com0",
            "com1",
            "com2",
            "com3",
            "com4",
            "com5",
            "com6",
            "com7",
            "com8",
            "com9",
            "com\u00b9",
            "com\u00b2",
            "com\u00b3",
            "lpt0",
            "lpt1",
            "lpt2",
            "lpt3",
            "lpt4",
            "lpt5",
            "lpt6",
            "lpt7",
            "lpt8",
            "lpt9",
            "lpt\u00b9",
            "lpt\u00b2",
            "lpt\u00b3"
        ],
        "memories.vod.disable": false,
        "DOMAIN": "files.qto.company",
        "AIO_VERSION": "v12.9.2"
    }
}

List of activated Apps

Enabled:
  - activity: 6.0.0
  - admin_audit: 1.23.0
  - calendar: 6.3.0-rc.1
  - cloud_federation_api: 1.17.0
  - comments: 1.23.0
  - dav: 1.36.0
  - federatedfilesharing: 1.23.0
  - files: 2.5.0
  - files_external: 1.25.1
  - files_fulltextsearch: 33.0.0
  - files_pdfviewer: 6.0.0
  - files_sharing: 1.25.2
  - files_trashbin: 1.23.0
  - files_versions: 1.26.0
  - forms: 5.2.6
  - fulltextsearch: 33.0.0
  - fulltextsearch_elasticsearch: 33.0.0
  - integration_giphy: 2.2.0
  - logreader: 6.0.0
  - lookup_server_connector: 1.21.0
  - nextcloud-aio: 0.8.0
  - notes: 4.13.1
  - notifications: 6.0.0
  - notify_push: 1.3.1
  - oauth2: 1.21.0
  - profile: 1.2.0
  - provisioning_api: 1.23.0
  - richdocuments: 10.1.2
  - serverinfo: 5.0.0
  - settings: 1.16.0
  - spreed: 23.0.3
  - support: 5.0.0
  - suspicious_login: 11.0.0
  - tasks: 0.17.1
  - text: 7.0.0
  - theming: 2.8.0
  - twofactor_backupcodes: 1.22.0
  - updatenotification: 1.23.0
  - user_ldap: 1.24.0
  - user_status: 1.13.0
  - viewer: 6.0.0
  - workflowengine: 2.15.0
Disabled:
  - app_api: 33.0.0 (installed 32.0.0)
  - bruteforcesettings: 6.0.0 (installed 6.0.0)
  - circles: 33.0.0 (installed 31.0.0-dev.0)
  - contactsinteraction: 1.14.1 (installed 1.11.0)
  - dashboard: 7.13.0 (installed 7.12.0)
  - encryption: 2.21.0
  - federation: 1.23.0 (installed 1.20.0)
  - files_downloadlimit: 5.1.0 (installed 3.0.0)
  - files_reminders: 1.6.0 (installed 1.3.0)
  - firstrunwizard: 6.0.0 (installed 3.0.0)
  - nextcloud_announcements: 5.0.0 (installed 2.0.0)
  - password_policy: 5.0.0 (installed 2.0.0)
  - photos: 6.0.0 (installed 5.0.0-dev.1)
  - privacy: 5.0.0 (installed 2.0.0)
  - recommendations: 6.0.0 (installed 3.0.0)
  - related_resources: 4.0.0 (installed 1.5.0)
  - sharebymail: 1.23.0 (installed 1.20.0)
  - survey_client: 5.0.0 (installed 2.0.0)
  - systemtags: 1.23.0 (installed 1.20.0)
  - testing: 1.23.0
  - twofactor_nextcloud_notification: 7.0.0
  - twofactor_totp: 15.0.0 (installed 12.0.0-dev)
  - weather_status: 1.13.0 (installed 1.10.0)
  - webhook_listeners: 1.5.0 (installed 1.3.0)

Nextcloud Signing status

No errors have been found.

Nextcloud Logs

Additional info

No response