@asterwisp +1 on this issue, I'm having this on Windows 10 + Opera GX and whenever I alt tab to a fullscreen app my opera gx flashes too and it's really annoying if I start paying attention to it. One example that triggers it is just alt tabbing in and out of Genshin Impact that's set to "1920x1080 Fullscreen". I'd hope there's at least a way to fully disable opera's taskbar flashing if it's going to be this defective...