I did have one student fail for using AI. It was such an awful submission.
I also had multiple students that I believe used AI to help in the creation of some assignments, but I built in presentations including Q&A to ensure they could speak to the subject.
No situation I came across was bad enough to warrant expulsion except for one case of blatant plagiarism in which a student had accessed another students computer and reworded a major assignment, but this had nothing to do with AI.
Bonus: I regularly ran in-class activities where I'd split the class into small groups on the Human side and on the AI side and give them the same tasks to complete. Humans always won.
"They had similar usernames, he's probably a pedophile too, he deserved his sentence and I'll lock him up again if his name crosses my desk. He's on thin ice."