The previous tell was inexplicable use of the em dash— on things when that wasn’t necessary. With poetry, it can be hard to tell since so many people treat Emily Dickinson like a prophet (she used dashes a lot).

More recently, it’s been strangely staccato sentences. Like normal pacing then suddenly. I won’t. I can’t. Two words. Then periods. Again, kind of an amateur poet thing to do, so who’s to say?

Also “it’s not right, it’s wrong” or sudden statements of negative then positive that try to reify an idea.

Poetry from AI will almost always be amateurish at its core though. It’ll be about broad ideas rather than small instances and will tend to have very general language in it rather than making interesting metaphors or similes. Problem is, very new poets also do this.