Should AI Assisted / Hybrid Papers be Accepted by Professors?

So, I am helping my professor check his students papers as his teaching assistant. While I have to admire the higher quality of writing and research that comes out of the students these days, my problem is that the papers are practically no longer written by the students. Some just give the AI the full prompts for the research and then pass it off as their work, which to me is worse than plagiarism. Others, write half the paper and then let AI help with the rest. Some, use AI to polish their work.

How can I tell if the student actually learned something from the written task or not? How can I give them a fair grade when the AI detector flags their work? Should we accept these sort of AI assisted writing or not? Isn't AI written papers a disservice to the learning process of the students?

I think they should not. Universities must have a form of AI-writing detection (I know they have it but it may still not be efficient). Otherwise, students go the easiest route and plagiarize whatever they can.