[Bug]: Canadian locale is incorrect

⚠️ 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

The English (Canadian) locale is incorrect. The 12h clock is discouraged, but allowed. However, the locale used in Nextcloud should use the 24h clock, since the 24h clock is the recommended way to represent time.

https://www.canada.ca/en/government/system/digital-government/digital-government-innovations/enabling-interoperability/gc-enterprise-data-reference-standards/data-reference-standard-date-time-format.html

A.5 Time elements

A.5.1 An all-numeric time consists of the following time elements from left to right:
    A.5.1.1 Two digits between 00 and 23 to represent “hour”
    A.5.1.2 Two digits between 00 and 59 to represent “minute”
    A.5.1.3 Two digits between 00 and 59 to represent “second”
A.5.2 If a time zone is needed for the recording of time, the offset from the UTC standard consists of:
    A.5.2.1 A “+” if the time zone comes before UTC
    A.5.2.2 A “–” if the time zone is after UTC (all of Canada is after UTC)
    A.5.2.3 Two digits to represent “hour”
    A.5.2.4 Two digits to represent “minute”

A.6 Time separators

A.6.1 A colon “:” is to be used as a delimitator. If it is not used, then a capital “T” shall be inserted at the beginning of the string.

The Government of Canada specifies the ISO 8601 format for all-numeric dates (YYYY-MM-DD; for example, 2023-12-17). It recommends writing the time using the 24-hour clock (05:37) for maximum clarity in both Canadian English and Canadian French, but also allows the 12-hour clock (5:37 a.m.) in English.

Steps to reproduce

1. Go to Personal Info
2. Select Locale: English (Canadian)

Expected behavior

The preview should show 2025-07-15 HH:MM:SS and the locale use the 24h clock.

Nextcloud Server version

31

Operating system

Other

PHP engine version

PHP 8.3

Web server

Apache (supported)

Database engine version

MySQL

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

Fresh Nextcloud Server install

Are you using the Nextcloud Server Encryption module?

Encryption is Disabled

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***",
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "mysql",
        "version": "31.0.7.1",
        "installed": true,
        "forcessl": true,
        "loglevel": 0,
        "maintenance": false,
        "trusted_domains": [
            "***REMOVED SENSITIVE VALUE***"
        ],
        "share_folder": "\/Shared",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "logdateformat": "Y-m-d H:i:s O",
        "logtimezone": "Europe\/Vienna",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpmode": "sendmail",
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "mail_domain": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpsecure": "ssl",
        "memcache.local": "\\OC\\Memcache\\APCu",
        "memcache.locking": "\\OC\\Memcache\\Redis",
        "filelocking.enabled": true,
        "redis": {
            "host": "***REMOVED SENSITIVE VALUE***",
            "port": 0,
            "timeout": 0
        },
        "appstore.experimental.enabled": true,
        "trashbin_retention_obligation": "auto",
        "updater.release.channel": "stable",
        "integrity.check.disabled": true,
        "htaccess.RewriteBase": "\/",
        "overwrite.cli.url": "***REMOVED SENSITIVE VALUE***",
        "auth.bruteforce.protection.enabled": false,
        "simpleSignUpLink.shown": false,
        "upgrade.disable-web": true,
        "theme": "my",
        "mail_smtpauthtype": "PLAIN",
        "mail_smtpauth": 1,
        "mail_sendmailmode": "smtp",
        "filesystem_check_changes": 0,
        "mysql.utf8mb4": true,
        "connectivity_check_domains": [
            "***REMOVED SENSITIVE VALUE***"
        ],
        "default_phone_region": "CA",
        "trusted_proxies": "***REMOVED SENSITIVE VALUE***",
        "maintenance_window_start": 3,
        "app_install_overwrite": [
            "forms"
        ]
    }
}

List of activated Apps

Enabled:
  - activity: 4.0.0
  - admin_audit: 1.21.0
  - announcementcenter: 7.1.4
  - app_api: 5.0.2
  - appointments: 2.4.5
  - bookmarks: 15.1.2
  - bruteforcesettings: 4.0.0
  - calendar: 5.3.5
  - circles: 31.0.0
  - cloud_federation_api: 1.14.0
  - comments: 1.21.0
  - contacts: 7.1.5
  - contactsinteraction: 1.12.0
  - dav: 1.33.0
  - federatedfilesharing: 1.21.0
  - federation: 1.21.0
  - files: 2.3.1
  - files_downloadlimit: 4.0.0
  - files_external: 1.23.0
  - 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: 5.1.2
  - logreader: 4.0.0
  - lookup_server_connector: 1.19.0
  - nextcloud_announcements: 3.0.0
  - notes: 4.12.2
  - notifications: 4.0.0
  - notify_push: 1.1.0
  - oauth2: 1.19.1
  - password_policy: 3.0.0
  - phonetrack: 0.8.2
  - photos: 4.0.0
  - polls: 8.1.2
  - privacy: 3.0.0
  - profile: 1.0.0
  - provisioning_api: 1.21.0
  - quota_warning: 1.21.0
  - related_resources: 2.0.0
  - serverinfo: 3.0.0
  - settings: 1.14.0
  - sharebymail: 1.21.0
  - side_menu: 5.1.1
  - systemtags: 1.21.1
  - tasks: 0.16.1
  - text: 5.0.0
  - theming: 2.6.1
  - twofactor_backupcodes: 1.20.0
  - twofactor_totp: 13.0.0-dev.0
  - twofactor_webauthn: 2.2.0
  - updatenotification: 1.21.0
  - viewer: 4.0.0
  - weather_status: 1.11.0
  - webhook_listeners: 1.2.0
  - workflowengine: 2.13.0
Disabled:
  - dashboard: 7.11.0 (installed 7.0.0)
  - encryption: 2.19.0
  - impersonate: 2.0.0 (installed 2.0.0)
  - recommendations: 4.0.0 (installed 0.5.0)
  - support: 3.0.0 (installed 1.4.0)
  - survey_client: 3.0.0 (installed 0.1.5)
  - suspicious_login: 9.0.1
  - twofactor_nextcloud_notification: 5.0.0
  - user_ldap: 1.22.0
  - user_status: 1.11.0 (installed 1.0.1)

Nextcloud Signing status

No errors have been found.

Nextcloud Logs

no entries in log

Additional info

No response

Start from the Personal Info locale selector and the English (Canadian) preview described in the issue, then locate where that locale's date and time format is defined. Done means the preview uses an ISO-style date and a 24-hour time for English (Canadian), with the locale behavior verified in the applicable test coverage.