GitLab has remediated an issue in GitLab EE affecting all versions from 16.10 before 18.9.7, 18.10 before 18.10.6, and 18.11 before 18.11.3 that when instance-level approval rule editing prevention was enabled, could have allowed an authenticated user with Maintainer permissions to modify or delete project approval rules due to missing authorization checks.
Upgrade to versions 18.9.7, 18.10.6, 18.11.3 or above.