Did you ever resolve this issue? Just happened to me out of nowhere. The top half looks almost cartoonish. I actually thought I had accidentally pressed a filter setting but I see it's a glitch.
I am facing this issue as well. From what i can tell it is a software issue. I have done a reset via settings, but would like to basically reinstall oero on my phone. I have seen a number of methods online but the sites i e found are all about upgrading from one version to the next. Is there a place i can download the oreo firmware for the sm-n950u1?
Give this a shot; Settings>apps>3 vertical dots>Show system apps> Camera>Storage>Clear Data/Cache