So I decided to give a try to Opera GX since old Opera can't fix full screen close button for years. Yep, the button works fine in GX, but... each time I open new page, it briefly flashes white. Makes my eyes hurt, since I use dark mode. Hours of googling, and I've found that it might be a chromium issue. The problem is - it never happened in my old Opera! Only in GX. I tried all kinds of sorcery - extensions, flags, css, and gave up. Does not worth it. Firefox, here we go.