Amazon eng did some research and found the number of comments in a code review is proportional to the number of lines changed. Huge CRs get little comments. Small CRs get a lot of comments. At Amazon, it's common to have a 150 to 300 line limit to changes. It depends on the team.
In your case, I'd just reject it and ensure repo merges require your approval.
In your case, I'd just reject it and ensure repo merges require your approval.