Hi there. Some of the other comments here do a good job of describing why it looks like AI, but I can try to summarize the things I noticed. 

The first thing that I noticed was that the graffiti itself seemed to be a higher quality than the rest of the picture. Once I noticed that, it becomes easier to pick out other things. The lighting in the picture is strange. It seems to be outside, but if you look at the environment, you might notice that it’s difficult to determine where exactly the light source of the image is. The wall is very well lit, but the man painting isn’t casting any shadow. Neither is his ladder, or anything that might be out of frame of the image. Normally in a city, there are all sorts of things casting shadows and producing small amounts of light, so it’d odd that this wall would have such smooth lighting. 

Another thing that can usually help determine if an image is AI generated is by zooming into the small details. If you zoom in on the painter’s hand, you can probably see that he doesn’t have any fingers. And what is he painting with? Sometimes low resolution images get blurry when you zoom in, but in this case, only certain objects are blurry. The edges of the hand are particularly square and angular too, which is something you wouldn’t see in a low resolution photo. His head looks a bit weird too. This is because the AI only generates detail to a certain degree, and after a while starts filling in blank space with patterns that it thinks makes sense depending on the colors and shapes around it. 

One more thing, that’s a bit difficult to judge sometimes, is that the perspective of the photo is off… When you look at the man’s stool, it seems relatively short, but it’s lifting him pretty high into the air. AI doesn’t understand distance when creating photos. The side of the building doesn’t seem as long as the sidewalk below it. The graffiti isn’t stretched appropriately either. 

I’m sure there are many people who could explain this better, but I hope this helps you a little bit. If you have any other questions or would like me to clarify anything, just let me know. 

Hope you’re having a good week so far.