How's grace period going?
Filtering by noai tag filters out 99% of games that were made before or not aware of tag's existence.
Viewing post in Prevent Itch.io from AI slop
The disclosure by meta information is only mandatory for assets. And the grace period is not over, obviously.
But you now at least see in all projects information about the disclosure in the more info box. It's either yes, no or nothing. Nothing means the ai disclosure was not filled out.
And you are right, the no-ai only works with new games that bothered to fill it out. It is not the negation of ai-generated.