happened to me too using Opensuse Tumbleweed with kernel 5.1.7 and MESA 19.0.5,
I have been try to disable power management in amdgpu via kernel paramater but
still happen.
this happen to me while I play some game(s) such Mutant Zero Year and Uboat on
the STEAM, while other games seems doesnt trigger this static greyed display
such as The Witcher 3
I cant log/reproduce any error messages since I'm using the laptop display
(Acer Predator Helios 500 Ryzen 2700 with vega56)
but maybe I can show my recorded video taken from my phone while this display
glitch happened.