In principle, I think having these tags would be a good thing. I don't know about making it a hard requirement though as in many cases, posters may not know for sure whether AI was used or not.

I think it could also be relevant to know how AI was used. For me, there's a big difference between a vibe-coded project full of generated assets and a game where AI was just used for something like debugging.

So maybe, one way to go about it is to have a short Steam-Style "AI-disclosure" in the description for games, where that information is available or obvious. Like "Uses AI-generated 2D-Assets" or "Uses AI for text translations" etc. But as I wrote, I would make it a suggestion rather than a requirement.