Failing to delete a user

Nextcloud version: 25.0.2
Operating system and version:
Apache or nginx version:
PHP version: 8.1.13

The issue you are facing:

Is this the first time you’ve seen this error? (Y/N): N

Steps to replicate it:
in our project cloud (version 25.0.2) I have created several users. Two of them cannot be deleted, nor can I change the storage quota or password. Only assigning or removing user groups works.

Restarting the Apache server did not work as recommended here (Failing to delete a user : An error occured during the request. Unable to proceed). And deleting the user folders in the data directory does not work either.

So I tried to delete the two users via the database (accounts and accounts_data). phpMyAdmin returns a success message and the users are deleted for now. If I now reload the Nextcloud user page, the users are still there. And as if by “magic” the users are also created again in the database.

As I said, only two users are affected, not all. Do you know the problem and does anyone have a solution?

The output of your Nextcloud log in Admin > Logging:
no message

only when I delete the user directory: Error: disk_free_space(): No such file or directory at /var/www/vhosts/