Oh yeah I forgot about the AI training part. Thanks for reminding me. There are loads of scam-y practices going on there. If trained using only art with permission then I wouldn't find it unethical. But we know that's not going to happen and is practically impossible to inspect.
Viewing post in A free set of... cute monsters?
I too would be okay with A.I. if the developers had just used images they had permission to use (or that were in the public domain). But, yeah, pandora's box is already open, and there's not much we can do now but encourage people to use A.I. art responsibly (e.g. for brainstorming, as a placeholder, etc.)