I am having the same bug but I have only seen it when watching Youtube. It started recently in the last two weeks maybe, and it is only on my second display. However that could just be because I only watch videos on my secondary display.
My specs are as follows:
Intel i5 9400f
NVIDIA RTX 2060 Super
16GB RAM
1080p 144hz monitor and a 1080p 60hz monitor
I don't use RGX, my GPU is overclocked, and XMP is enabled. My hypothesis though is that this doesn't have anything to do with hardware and is likely a Nvidia driver bug specific to Opera GX. I would like to know what websites cause this for you guys, and I think that ReelBigDan is probably on to something with the issue stemming from website elements.