This is a representation of the data density in the jpeg compression. Photos that have been edited and recompressed will often have a different level of detail in the edited regions, or a conspicuous lack of detail as seen in the poster glass here.
I'm not an expert by any stretch, but it looks fairly legit.
You can see the lighting of the picture is similar to the lighting of the scene/world, including some mild reflection of the ground and cars in front of the dark parts of the picture (his black jacket).
These are very subtle details that, while always possible to fake, would have been a pretty serious investment in time and energy to have done.