Accept approval of merge requests by their committers.
After adding commits to an MR one can't approve anymore. I think this is not ideal, since sometimes it is much more convenient when an approver makes a small change instead of adding a comment. Note that the author of the MR should still not be able to approve.
This setting can be modified in gitlab, see https://docs.gitlab.com/ee/user/project/merge_requests/merge_request_approvals.html#prevent-approval-of-merge-requests-by-their-committers