This has already happened in academia where certain professors just dump(ed) their student's essays into ChatGPT and ask it if it wrote it, and fail anyone who had their essay claimed by ChatGPT. Obviously this is beyond moronic, because ChatGPT doesn't have a memory of everything it's ever done, and you can ask it for different writing styles, and some people actually write pretty similar to ChatGPT, hence the fact that ChatGPT has its signature style at all.
I've also heard of artists having their work removed from competitions out of claims that it was auto-generated, even when they have a video of them producing it stroke by stroke. It turns out, AI is generating art based on human art, so obviously there are some people out there whose stuff looks like what AI is reproducing.