On any video player that has a gradient, it breaks when I full-screen the video, showing as solid semi-opaque bars instead of the intended gradients. This happens on any video player I've used that has a gradient, and is most noticeable on YouTube due to the double gradient. It displays normally when I use snipping tool, so apologies for the bad quality on the second image. I use Ublock Origin and Dark Reader, but this behaviour doesn't change when either is disabled.