@bigbro Hello! I use to have this problem as well, and this is due to the automatic dark mode feature GX has. To get rid of this issue, right click on your screen (inside YouTube) and click "Disable force dark page." Hopefully this helps!
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RE: [Solved] Youtube has a white fade overlay on the videosOpera for Windows
Notifications not working?Opera for Windows
I've had GX for about a month now, and I cannot get notifications to work. I have them enabled through everything, but they don't ever show up. I don't have this problem with other browser, just Opera. Any tips?