Weird darker bar and navigation buttons appearing over other apps

[MurdockWolfgang]

Recently I've noticed that a dark low opacity stripe has appeared on my phone, from the top to about a quarter of the top of the phone, it is constantly there, although it is a lot easier to see on darker backgrounds, and alongside it there are transparent navigation buttons on the same spot they normally are. I've already done the usual reboot, changed launchers and all that, anyone else having this problem or know how to fix it? Can't really post a picture of it since screenshotting doesn't actually show the dark areas