[Bug]: More storage space than available can be occupied by the copy function

⚠️ 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

Dear Nextcloud,

I'd like to report a server bug for you. We can exceed the user quota if we use the copy function and copy files to another folder.

Steps to reproduce

1. Login
2. Upload as many files until the storage space is full
3. Create another empty folder
4. Mark the previously uploaded files and copy them into the newly created folder

Nextcloud logs:
There's no log for this issue

Expected behavior

storage space full

Installation method

None

Nextcloud Server version

25

Operating system

None

PHP engine version

None

Web server

None

Database engine version

None

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

No response

List of activated Apps

No response

Nextcloud Signing status

No response

Nextcloud Logs

No response

Additional info

No response

Start by reproducing the listed steps on Nextcloud Server 25: fill a user's storage, create a folder, and copy the existing files into it. Trace the server-side copy operation and quota handling; done means copying cannot cause storage usage to exceed the user's quota. No source files or tests are named in the issue.