[Bug]: Date of birth not respecting user locale

⚠️ 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

In the user settings the date of birth field is not respecting the setting choosen locale.

Steps to reproduce

1. Go to user settings
2. Change locale to German (Switzerland)
3. Look at date of birth

Expected behavior

The date format would be the same as shown in the locale.

Nextcloud Server version

31

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?

None

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": {
        "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
            }
        ],
        "appsallowlist": false,
        "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": "next.foobar.vip",
        "overwriteprotocol": "https",
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "localhost",
            "next.foobar.vip"
        ],
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "pgsql",
        "version": "31.0.8.1",
        "overwrite.cli.url": "https:\/\/next.foobar.vip\/",
        "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,
        "updater.release.channel": "stable",
        "updatedirectory": "\/nc-updater",
        "loglevel": "2",
        "app_install_overwrite": {
            "0": "nextcloud-aio",
            "1": "extract",
            "2": "files_archive",
            "3": "files_reader",
            "6": "files_fulltextsearch",
            "7": "files_fulltextsearch_tesseract",
            "8": "fulltextsearch_elasticsearch",
            "9": "onlyoffice"
        },
        "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": {
            "1": "OC\\Preview\\Image",
            "2": "OC\\Preview\\MarkDown",
            "3": "OC\\Preview\\MP3",
            "4": "OC\\Preview\\TXT",
            "5": "OC\\Preview\\OpenDocument",
            "6": "OC\\Preview\\Movie",
            "7": "OC\\Preview\\Krita",
            "0": "OC\\Preview\\Imaginary",
            "23": "OC\\Preview\\ImaginaryPDF"
        },
        "enable_previews": true,
        "upgrade.disable-web": true,
        "mail_smtpmode": "smtp",
        "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",
        "allow_local_remote_servers": true,
        "davstorage.request_timeout": 3600,
        "htaccess.RewriteBase": "\/",
        "dbpersistent": false,
        "files_external_allow_create_new_local": false,
        "trusted_proxies": "***REMOVED SENSITIVE VALUE***",
        "preview_imaginary_url": "***REMOVED SENSITIVE VALUE***",
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "mail_sendmailmode": "smtp",
        "mail_domain": "***REMOVED SENSITIVE VALUE***",
        "mail_smtphost": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpport": "587",
        "mail_smtpauth": 1,
        "mail_smtpname": "***REMOVED SENSITIVE VALUE***",
        "mail_smtppassword": "***REMOVED SENSITIVE VALUE***",
        "data-fingerprint": "f7bf3fdaf66aa60a897626e74ff677b5",
        "maintenance_window_start": 100,
        "auth.bruteforce.protection.enabled": true,
        "ratelimit.protection.enabled": true,
        "preview_imaginary_key": "***REMOVED SENSITIVE VALUE***",
        "documentation_url.server_logs": "https:\/\/github.com\/nextcloud\/all-in-one\/discussions\/5425",
        "onlyoffice": {
            "jwt_secret": "***REMOVED SENSITIVE VALUE***",
            "jwt_header": "AuthorizationJwt"
        },
        "updatechecker": false,
        "DOMAIN": "next.foobar.vip"
    }
}

List of activated Apps

Enabled:
  - activity: 4.0.0
  - admin_audit: 1.21.0
  - app_api: 5.0.2
  - assistant: 2.8.0
  - bruteforcesettings: 4.0.0
  - calendar: 5.5.5
  - circles: 31.0.0
  - cloud_federation_api: 1.14.0
  - comments: 1.21.0
  - contacts: 7.3.2
  - contactsinteraction: 1.12.0
  - dashboard: 7.11.0
  - dav: 1.33.0
  - dav_push: 0.0.3
  - extract: 1.3.6
  - federatedfilesharing: 1.21.0
  - federation: 1.21.0
  - files: 2.3.1
  - files_automatedtagging: 2.0.0
  - files_downloadlimit: 4.0.0
  - files_fulltextsearch: 31.0.0
  - files_fulltextsearch_tesseract: 27.0.1
  - files_pdfviewer: 4.0.0
  - files_reminders: 1.4.0
  - files_sharing: 1.23.1
  - files_trashbin: 1.21.0
  - files_versions: 1.24.0
  - firstrunwizard: 4.0.0
  - forms: 5.2.0
  - fulltextsearch: 31.0.0
  - fulltextsearch_elasticsearch: 31.0.0
  - integration_onedrive: 3.4.0
  - integration_openai: 3.7.1
  - logreader: 4.0.0
  - lookup_server_connector: 1.19.0
  - mail: 5.5.5
  - nextcloud-aio: 0.8.0
  - nextcloud_announcements: 3.0.0
  - notes: 4.12.3
  - notifications: 4.0.0
  - notify_push: 1.2.0
  - oauth2: 1.19.1
  - onlyoffice: 9.10.0
  - password_policy: 3.0.0
  - privacy: 3.0.0
  - profile: 1.0.0
  - provisioning_api: 1.21.0
  - recommendations: 4.0.0
  - related_resources: 2.0.0
  - serverinfo: 3.0.0
  - settings: 1.14.0
  - sharebymail: 1.21.0
  - sharepoint: 1.19.0
  - sociallogin: 6.2.2
  - support: 3.0.0
  - survey_client: 3.0.0
  - suspicious_login: 9.0.1
  - systemtags: 1.21.1
  - text: 5.0.0
  - theming: 2.6.1
  - twofactor_backupcodes: 1.20.0
  - twofactor_totp: 13.0.0-dev.0
  - updatenotification: 1.21.0
  - user_status: 1.11.0
  - viewer: 4.0.0
  - webhook_listeners: 1.2.0
  - workflow_pdf_converter: 2.0.0
  - workflowengine: 2.13.0
Disabled:
  - encryption: 2.19.0
  - files_archive: 1.2.7 (installed 1.2.7)
  - files_external: 1.23.0
  - files_rightclick: 0.15.1 (installed 1.6.0)
  - photos: 4.0.0 (installed 4.0.0-dev.1)
  - tasks: 0.16.1 (installed 0.16.1)
  - twofactor_nextcloud_notification: 5.0.0
  - user_ldap: 1.22.0
  - weather_status: 1.11.0 (installed 1.11.0)

Nextcloud Signing status

No errors have been found.

Nextcloud Logs

Additional info

No response

Reproduce the issue from user settings by changing the locale to German (Switzerland) and checking the date-of-birth field. Trace the user settings date formatting and locale handling; done means the displayed date format matches the selected locale.