Preventing users to create top-level groups through the Admin UI does not work

After reading about "Admin Area setting to prevent users from creating groups" in the GitLab 15.5 release notes, I just deactivated Allow users to create top-level groupsand saved as implemented in #367754 (closed).

After that and veryfying the option being set and actually saving a second time just to be sure, I used my regular non-admin account and was still able to create a top-level group. To verify, a colleague with even lesser permissions was also still able to create a top-level group.

Version of our third party-hosted instance: 15.5.2-ee We did not restart GitLab, though.