If it is posted as AI art, I don't have an issue. As others have commented, there are many valid use cases for it, and like any form of art, it's not inherently good or bad.
The problem I have is when it gets mixed in with real images and there is no differentiation.
I do the bulk of posting at !superbowl@lemmy.world, and one thing I do is promote raptor rescue operations, so I'm subbed to 60ish Facebook feeds for the various shelters I get news and photos from. As a result, I get recommended near every owl photo posted to Facebook.
Now, getting real image groups recommended to me is great. I just got a bunch of great images I'd never seen from a photography group it recommended. But I get so many obvious fakes posted as real images, and another larger group where it's hard to tell.
I'm just someone that wanted to keep a Lemmy community going after the original buzz died down. I'm not an animal expert or a photographer, so I can't always pick out what is a really good photo vs post processing, vs downright fake. I want to keep the legitimacy of what I do post intact, because I work hard to keep content factual. I pass on what could be some really great photos because I can't always say they're real.
Plus it would be nice to have them separate from real images in general. Sometimes I would like to see some AI owl pics, but once random groups or repost bots start mixing things in randomly, it makes people question things.