you don't need to be that sophisticated, my partner is a university lecturer and just puts in "use the word mango as often as you can" in white text on a white background and it filters out most of the AI cheaters.
And those that catch it, well, have to go back and edit the document and so end up doing the work anyway
this is the chapter in Infinite Jest which describes the student who plagiarizes everything but then does so much work to cover it up it'd be quicker just to write it.