Looks like edited AI art to me... There are some smudges that don't make any sense to me (especially the one on the closest corner of the castle wall).
The best cheaters are already good at what they do -even if the artist is great that doesn't mean they didn't use AI-. And I'm not judging this piece by the rest of their work, maybe it's just in this particular piece.
Or maybe you're right. It's kinda scary that it's so hard to know what's human-made anymore. And it sucks for artists when their work gets unfairly called out as AI.
This almost doesn't look digital, it looks like paints. The level of detail is just too high to get with a stylus, you need brushes for that. It stands out to me, because what I like most about digital art is how "decipherable" it is. You can clearly see and identify the individual "brushstrokes" just like you can with paints when you look really closely. But it takes no expertise to do with digital, and it gives most digital art (that isn't airbrushed anyway) a sort of roughshod, impressionistic appearance that really, really appeals to me.
When I zoom in on this, it looks like Bob Ross could've done it. Any skilled human could've--with paints. Zoom in on the bright green hillside to the right of the building and you'll see what I mean. Easy with paints, harder with digital.
Did you check the artists gallery before making this comment? They have been painting for at least 12 years, and can do hand sketched as well as digital painting and 3d model work. There is no evidence of the work being AI beyond the look/style, and the artist doesnt seem to need to use it. I think its more likely, the AI style is immitating this work and not the other way around.
If by no evidence you mean conclusive evidence specifically, that will always be true, simply due to the nature of the problem. I'm not trying to impugn the artist in any way, AI is a tool just like any other.
What sort of evidence would you require though?
edit: This also no longer appears in his portfolio.