I tried this and found that there are a set of potentially good candidates who simply cannot bring themselves to criticize anything in front of an interviewer due to the power dynamics of the interviewer/interviewee relationship.
"Imagine that this code was written by a junior dev; review it and tell me how it can be improved, where the problems are, and other feedback".
"We just hired a new intern and he pushed this PR. I need you to help me review this code for issues and make sure it's production ready".