if you use reachability (double tap on home button) with iOs 10.2.... only the icons move down and not the wallpaper.. se no more black effect on the upper half of the screen
I believe it's like that when you are on the home screen, while it's basically black background while you do it within an app.
Can't say I see mine as blurred or anything. Just a dark background and that's it (while my wallpaper has some variations to it).