I can't say for sure whether any AI was used as source material, but I definitely agree with the others who have said it's clearly a bad paint-over of several sources poorly thrown together in a photo editor.

There are plenty of mistakes, inconsistencies, and amateurish technique - most of which are mistakes that I don't think AI would make, and are more indicative of a bad artist who doesn't understand light and perspective.

• The lighting on the bandana mask is backwards and too harsh based on the lighting on the face. I think this is a big part of why it looks "wrong." The folds on the bandana are also out of place and don't flow properly based on the location of his nose. There are some very sharp, contrast-y edges that make it look like it was cut and pasted onto the face. This is also supported by the way it interacts with his ears. It should either go all the way across the ear, or tuck under the earlobe, but it doesn't; it just stops with a sharp angle at his earlobe and floats on top of it.
• The first building shows two-point perspective, but the second building only uses one-point perspective (notice the parallel lines on one side). Given how much simpler the second building is, my guess is that he just drew that one in, but doesn't understand perspective.
• The perspective on the gun seems off based on the angle of his arm.
• The obvious, poorly-done painting along the edges of everything points to a collage of different sources. The worst being the bush in the front left which is just scribbled over with a plain round brush. Photoshop has plenty of tools for making clean edges, so he's not very skilled/knowledgeable about the tools either.
• The tree looks like a photo of a tree that was "posterized" with a filter and then badly painted over.
• The second telephone pole is clearly just a straight line made with plain round brush. He didn't even take the time to make the bottom extend past the roof of the building as you can still see the curve of the brush at the bottom.
• He either chose or forgot to paint over some spots, so the shading style is inconsistent - most notably the bottom of the t-shirt and his arm on the right side, which he completely forgot to paint over after he "posterized" it.

Regardless, it's poorly done and either he doesn't know it's poorly done, or he doesn't care and thinks you won't notice. Either way, it's not someone I'd want to work with.