I think it's important to understand/discover what AI Clear does best - imo the website does a fairly good job of showing that - there are no super-noisy before images or such. And in my experience it does what is advertised - dealing with average noise, slight lack of focus, chromatic aberration - really well.
I have been testing it with 8 year old images from a DSLR to more recent ones from much higher resolution cameras, to phone photos and in general the ability to fix a whole bunch of issues with a click or two (basically picking medium or high model if low does not do the trick) is very impressive. And, in theory, if they keep on adding photos to the model and "teaching" the AI it could only improve.
Hopefully they keep on doing that - it would probably be easy to get users to submit pairs of images taken with high ISO and lots of noise and clean ones. I would gladly do that if there was a chance of better results.