I am applying Photo AI to old B&W pictures which are both grainy and sometimes out of focus. The tool does a great job identifying and recovering the faces, getting rid of the grain and bringing them into sharp focus. Unfortunately it only does this in a fuzzy rectangle around the face. So there is an island of clarity which ends in a jagged boundary at the neck and in the middle of the hair at the top of the head and around the ears. If it is going to do such a great job there, it needs to do a similar job on the rest of the photo so it looks natural.
Topaz Photo AI v1.2.6 on Mac