[Bug]: Users showing used quota out of nowhere, with 0 files in their home (fresh accounts)

[solracsf]

⚠️ 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

Some existing users, and new users, are showing a 55,7 GB used quota out of nowhere.

No errors or warnings that could be related to this in the logs.

Problem appeared after upgrade from 30.0.14 to 30.0.15.

Remains after upgrade from 30.0.15 to 31.0.9.

Steps to reproduce

Even tough this is reproducible with new users, some existing users are observing the same behavior.

1. Create new user testing
2. Log in with that user, user shows 0 used quota
3. Scan user files with occ files:scan testing
4. Observe new used quota at 55,7 GB

# occ user:info testing
  - user_id: testing
  - display_name: testing
  - email: testing@gmail.com
  - cloud_id: testing@server.com
  - enabled: true
  - quota: 1000 GB
  - storage:
    - free: 10737418240
    - used: 0
    - total: 10737418240
    - relative: 0
    - quota: 10737418240
  - last_seen: 2025-09-15T05:40:55+00:00
  - user_directory: /var/www/data/testing
  - backend: Database

# occ files:scan testing -vv
Starting scan for user 1 out of 1 (testing)
        Folder  /testing/
        Folder  /testing/cache
        Folder  /testing/files

+---------+-------+-----+---------+---------+--------+--------------+
| Folders | Files | New | Updated | Removed | Errors | Elapsed time |
+---------+-------+-----+---------+---------+--------+--------------+
| 3       | 0     | 0   | 0       | 0       | 0      | 00:00:00     |
+---------+-------+-----+---------+---------+--------+--------------+

# occ user:info testing
  - user_id: testing
  - display_name: testing
  - email: testing@gmail.com
  - cloud_id: testing@server.com
  - enabled: true
  - quota: 1000 GB
  - storage:
    - free: 1013951105903
    - used: 59790718097
    - total: 1073741824000
    - relative: 5.57
    - quota: 1073741824000
  - last_seen: 2025-09-15T05:40:55+00:00
  - user_directory: /var/www/data/testing
  - backend: Database

Expected behavior

Correctly calculated quota

Nextcloud Server version

30

Operating system

Debian/Ubuntu

PHP engine version

PHP 8.3

Web server

Apache (supported)

Database engine version

MariaDB

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

Updated from a MINOR version (ex. 32.0.1 to 32.0.2)

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

[solracsf]

Root cause

The groupquota app installs OCA\GroupQuota\Wrapper\GroupUsedSpaceCacheWrapper around each member's home-storage cache. Its get() returns the affected_group group's pooled used space (~56 GB) as the size of every member's files folder.

IDK if this is something maintainers want to improve.

Disabling the groupquota app fixed it.