The organizers of game jams are looking for genuinely creative games. AI can't make those, since it can't make anything which isn't some kind of blend of the stuff it was trained with. So the game jam organizers might as well want to save themselves the time to review games that are just another version of regurgitated content.
Viewing post in Generative Ai for Game development
It should of course be obvious to come up with a game idea yourself and be creative, to participate in a jam.
But if you draw images by hand or use stock images, asset packs or use gen ai, does not change the creativity of the game itself. It depends on the jam what rules apply, and some jams even are about making games with ai.
And it also depends on the jam organizer why they would not want generative ai things in their jam or how they specify that in their rules. Or what type of ai usage they do not want.
This one here is rather interesting: No AI-generated art in-game, or the project page. You may use AI in design or code, but assets must be human-made. Tools that build the entire game from promps are also not allowed.
So you would be allowed to use an ai to design the actual game! The part that should be the most creative part, in my opinion. But you would not be allowed to use ai gen assets. Or use it to create your game page description.