I was the one that wrote "I don't really trust the source" in the rejection message.
So I checked the source, looking that it had an AI art (stolen from here), another stolen artwork (the original is post #6228589), and actual drawn artwork that looked different than this one. That's why I got wary.
Edit: Alright, turned out this was also stolen (the original is the parent). No surprise that this one was deleted from Pixiv.
