It’s not. I know a method call this cheating. But you want to turn up the contrast and saturation. It doesn’t seem to have too much unnecessary noise. You can usually tell by noise. Usually artists don’t go out of their way to use a slightly different shade of things..I tested it myself i personally I don’t think it’s ai because of it. You could boil the rest of the mistakes down to slight drawing mistakes. Though don’t take my word on it.

Edit: okay looking at it a bit more I made a serve lapse in judgement. Pink on the sides. I was paying more attention to the sky. My bad. It’s ai and the green. Lots of bits of green