I was hoping changing from HDMI to DisplayPort would sort out my screen issues. To a degree, it did.
I can now use my screen at full resolution using the amdgpu driver from Fedora repositories but the intermittent, incredibly irritating, sporadic blank screen issues persists.
Another suggestion that came up from a forum was to try X11 instead of Wayland to draw stuff, that helped with a wonky dialog issue, but still no fix for the sporadic blank screen.
Getting to the point I'm almost tempted to try another monitor in case it's not software. That would be surprising though.