I feel like restricting AI-generated posts to AI-labelled communities is the way to go.
I'm not a fan of AI artwork in general, but I feel so long as it's being restricted to certain communities and not left to move into other ones, then things are fine there. My main concern with AI artwork is that art is being sampled without the original artists' explicit permission a lot of the time, and while I understand people's trouble with niche interests at times, I feel that that personally curated content from an AI prompt is best kept privately than shared publicly, potentially in some way infringing on the original copyright.