[Bug]: after upgrading nextcloud to 28.0.11.1 it started adding all users to Circles groups twice while user was already being managed by LDAP groups

⚠️ 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

[root@nextcloud01 ~]# sudo -u apache php /var/www/html/nextcloud/occ status
  - installed: true
  - version: 28.0.11.1
  - versionstring: 28.0.11
  - edition: 
  - maintenance: false
  - needsDbUpgrade: false
  - productname: Nextcloud
  - extendedSupport: false

An administrator added you to group fa
October 21, 2024 4:09 PMyesterday

You have been added as member to group:fa by C Circles
October 21, 2024 4:09 PMyesterday

An administrator added you to group fa
October 21, 2024 3:53 PMyesterday

You have been added as member to group:SAML_fa by C Circles 

Steps to reproduce

1. have nextcloud ldap groups and saml auth configured
2. upgrade nextcloud to 28.0.11.1
3. watch all users get emails that it has been added to groups it was already in and now also having multiple duplicated groups.

Expected behavior

Not have duplicated groups and not sent emails to users

Nextcloud Server version

28

Operating system

RHEL/CentOS

PHP engine version

PHP 8.1

Web server

Nginx

Database engine version

MySQL

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

Upgraded to a MAJOR version (ex. 28 to 29)

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

[root@nextcloud01 ~]# sudo -u apache php /var/www/html/nextcloud/occ config:list system
{
    "system": {
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "localhost",
            "192.168.40.195",
            "nextcloud01.powercraft.lan",
            "nextcloud.powercraft.nl",
            "nextcloud.powercraft.org"
        ],
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "mysql",
        "version": "28.0.11.1",
        "overwrite.cli.url": "https:\/\/nextcloud.powercraft.org\/",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbport": "",
        "dbtableprefix": "oc_",
        "mysql.utf8mb4": true,
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "installed": true,
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "memcache.distributed": "\\OC\\Memcache\\Redis",
        "memcache.locking": "\\OC\\Memcache\\Redis",
        "memcache.local": "\\OC\\Memcache\\APCu",
        "redis": {
            "host": "***REMOVED SENSITIVE VALUE***",
            "port": "6379",
            "dbindex": "0",
            "timeout": "0.5"
        },
        "overwriteprotocol": "https",
        "htaccess.RewriteBase": "\/",
        "logtimezone": "Europe\/Amsterdam",
        "simpleSignUpLink.shown": false,
        "default_language": "en",
        "defaultapp": "files",
        "skeletondirectory": "",
        "mail_smtpmode": "smtp",
        "mail_domain": "***REMOVED SENSITIVE VALUE***",
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "mail_sendmailmode": "pipe",
        "ldapIgnoreNamingRules": false,
        "ldapProviderFactory": "OCA\\User_LDAP\\LDAPProviderFactory",
        "mail_smtpsecure": "tls",
        "mail_smtpauthtype": "LOGIN",
        "mail_smtpauth": "1",
        "mail_smtphost": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpport": "587",
        "mail_smtpname": "***REMOVED SENSITIVE VALUE***",
        "mail_smtppassword": "***REMOVED SENSITIVE VALUE***",
        "share_folder": "\/Shared",
        "maintenance": false,
        "loglevel": 2,
        "remember_login_cookie_lifetime": "1296000",
        "session_lifetime": "86400",
        "session_keepalive": true,
        "token_auth_enforced": false,
        "default_phone_region": "NL",
        "app_install_overwrite": [
            "richdocuments"
        ],
        "updatechecker": false,
        "tempdirectory": "\/srv\/storage\/nextcloud\/data\/tmp",
        "maintenance_window_start": 1,
        "lost_password_link": "disabled",
        "profile.enabled": false,
        "auth.webauthn.enabled": false
    }
}

List of activated Apps

[root@nextcloud01 ~]# sudo -u apache php /var/www/html/nextcloud/occ app:list
Enabled:
  - activity: 2.20.0
  - bruteforcesettings: 2.8.0
  - circles: 28.0.0
  - cloud_federation_api: 1.11.0
  - dav: 1.29.2
  - deck: 1.12.5
  - federatedfilesharing: 1.18.0
  - files: 2.0.0
  - files_external: 1.20.0
  - files_pdfviewer: 2.9.0
  - files_reminders: 1.1.0
  - files_sharing: 1.20.0
  - files_versions: 1.21.0
  - forms: 4.3.1
  - logreader: 2.13.0
  - lookup_server_connector: 1.16.0
  - oauth2: 1.16.4
  - password_policy: 1.18.0
  - provisioning_api: 1.18.0
  - related_resources: 1.3.0
  - richdocuments: 8.3.12
  - serverinfo: 1.18.0
  - settings: 1.10.1
  - sharebymail: 1.18.0
  - sharelisting: 1.2.0
  - text: 3.9.2
  - theming: 2.3.0
  - theming_customcss: 1.17.0
  - twofactor_backupcodes: 1.17.0
  - updatenotification: 1.18.0
  - user_ldap: 1.19.0
  - user_saml: 6.3.0
  - viewer: 2.2.0
  - workflowengine: 2.10.0
Disabled:
  - admin_audit: 1.18.0
  - comments: 1.18.0 (installed 1.10.0)
  - contactsinteraction: 1.9.0 (installed 1.1.0)
  - dashboard: 7.8.0 (installed 7.0.0)
  - encryption: 2.16.0
  - federation: 1.18.0 (installed 1.10.1)
  - files_rightclick: 0.15.1 (installed 1.6.0)
  - files_trashbin: 1.18.0 (installed 1.10.1)
  - firstrunwizard: 2.17.0 (installed 2.9.0)
  - nextcloud_announcements: 1.17.0 (installed 1.9.0)
  - notifications: 2.16.0 (installed 2.8.0)
  - photos: 2.4.0 (installed 1.2.1)
  - privacy: 1.12.0 (installed 1.4.0)
  - recommendations: 2.0.0 (installed 0.8.0)
  - support: 1.11.1 (installed 1.3.0)
  - survey_client: 1.16.0 (installed 1.8.0)
  - suspicious_login: 6.0.0
  - systemtags: 1.18.0 (installed 1.10.0)
  - twofactor_totp: 10.0.0-beta.2
  - user_status: 1.8.1 (installed 1.0.1)
  - weather_status: 1.8.0 (installed 1.0.0)

Nextcloud Signing status

No response

Nextcloud Logs

No response

Additional info

No response

The report names no source file or test; it provides only the occ status, configuration, app list, and reproduction steps. Start by reproducing the LDAP/SAML and Circles group-membership behavior after the upgrade, then trace where duplicate memberships and notifications are created. Done means existing memberships are not duplicated and users receive no redundant group emails.