If AI generated art is the main thing people are looking at, I don't really see anything wrong with mentioning it in their posts. There is no need to throw people in the dark and of they eventually discover later and they start feeling deceived. Most people don't even mind once the content itself makes sense. The argument usually starts when someone tries to pass generated images off as real photographs. Thats where trust begins to crack. I am afraid that online is already full of edited content and that's so dangerous. So, it is better make your audience know what they are seeing from the beginning.