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.