Hey, thanks for your reply! :)
It does not seem to be related to the post processing, and most players wont even notice - it looks as if the anti-aliasing is "smoothing out" some of the details out of the geometry/foliage. It's something i've noticed in many unreal 4 games (Paragon, PUBG) and can be solved by oversampling.
I've taken some screenshots for comparison: One is full AA with no post and second one is no AA with full post - especially look at the "cables" between the building and the foliage in the background.
By no way this is a dealbreaker - it's just a minor annoyance ;)