I was having a weird WebRender issue last year, except it was causing sudden reboots until the computer stayed powered off long enough for the GPU memory to be cleared. I had enabled WebRender in Linux (it's experimental, I know), and the computer would run fine for weeks at a time, then reboot out of nowhere. It would continue to reboot any time I opened firefox, sometimes a few minutes after starting firefox. The reboots would persist even when I would boot into Windows instead of Linux after one of the forced reboots. Once I narrowed it down to firefox causing the reboots, I started it in safe mode and disabled WebRender, and I haven't had any issues since. This was with a 1050TI graphics card.