@leocg its not and its not using the same account on other brosers youtube its normal
this make me sad cuz ai love using opera

@leocg Hi ! thx for reply most of this steps i already try, i even install opera gx to test it and have same problem with opera gx !

i try the other ones too and the problem persist,

i using windows 10

like you can see on this image again

aind its not just a border its cutting the video

I having a problem with youtube snice 2 or 3 days ago, with black borders on video cutting some parts, i found one topic from like 2019 i guess and they said to disable force dark mod, but mine its already disable and still getting this problem, i love this browser but this borders are start to get annoyng some one have a tip to help with that ?