As a manager of a full stack team, we've found AI falls short a lot more on front end. It has its weak points on both front and back, but the problems with backend are quite easy to feed back into it -- needs more performance, needs to pass this security audit, needs to deal with xyz system. The problems with frontend are more like this is ugly, it's clunky to use, people don't like it. People without years of frontend experience tend to lack the vocabulary required to get AI to fix it, period, and it ends up going around in loops.