@ghost81 Also experiencing the same issue, but for me it can also happen even when the window is in focus and I'm actively watching it. I haven't tested it in fullscreen. The issue seemed to start around the same time as well, maybe a couple of weeks ago or a little longer.
Tried all of the methods you've done as well with no success. I also tested with hardware acceleration turned on and off.
Opera (core: 85.0.4341.65)
Windows 10 Home 64bit
AMD Ryzen 7 5800X 8-Core
16GB RAM
RTX 3060TI 8GB