After using UE4 for a year I noticed weird and annoying shading/rendering artifacts which are pretty easy to reproduce. Basically just open any heavy and demanding ue4 level/scene and move the screenscale slider in the viewport (or go for 200 screenscale and play the level), you will probably get similar results. I am using 4.20.2 version of Unreal, but i think it doesn’t really matter because this thing happens on every version i tried.
Windows 10 Home 17763.134
Intel Core i5-4690k (OC to 4.3GHz)
Asus GeForce GTX 1070, Nvidia Driver 417.01
16 GB of RAM
I suspect that this is some driver issue because I saw some people facing similar trouble and downgrading the drivers has seem to fix the issue for them (not sure if this was the same problem I have).
Here are the screenshots of “artifacted” frames - Imgur: The magic of the Internet