Ideas to spot and block AI works in an open online arts and crafts competition?

One of my biggest fears is to be deceived by AI works. Physical ones are easier to spot, but like half of the competition will revolve about digital art, and that's becoming trickier by the day.

I'm thinking of some sort of user verification (not of private personal data but of public profiles on Behance, DeviantArt, ArtStation, Pixiv, and others) as a first measure, though that could turn be intensive and slow if the number of participants becomes high. And once verified there's not guaranty they won't resort to AI one day.

So then of course there could be a requisite to submit some kind of "proof", a set of images or animation/video of the whole process, and maybe have mods/members check it and vote (real or not) if the number of submissions is high and I need help.

The competition is free to enter, and not that having to pay an entry fee would stop all scammers. I'll go invitation-only shortly after the website is up and running because maybe slowing down registrations, and coming with more and better ideas, could help.

What do you think? How would you go about it?

Thanks in advance!