In all versions of GitLab CE/EE since version 8.0, when an admin uses the impersonate feature twice and stops impersonating, the admin may be logged in as the second user they impersonated, which may lead to repudiation issues.
https://gitlab.com/gitlab-org/gitlab/-/issues/339362
https://gitlab.com/gitlab-org/cves/-/blob/master/2021/CVE-2021-39896.json