I once submitted some code for review, in which the AI had inserted a recursive call to the same function being defined. The recursive call was completely unnecessary and completely nonsensical, but also not wrong per se - it just caused the function to repeat what it was doing. The code typechecked, the tests passed, and the line of code was easy to miss while doing a cursory read through the logic. I missed it, the code reviewer missed it, and eventually it merged to production.

Unfortunately there was one particular edge case which caused that recursive call to become an infinite loop, and I was extremely embarrassed seeing that "stack overflow" server error alert come through Slack afterward.