@ijpet This isnt a new issue, it existed for years now i think. Its due to wayland, when opera is set to run on wayland by setting ozone platform to auto or wayland this happens. Opera team haven't look into it, even me myself reported it in the forums.

why now its happening?
Well as far as i know Chrome made wayland default with v140. thereby opera now run on wayland by default

Its a good thing that it runs on wayland. I hope opera fixes it.

Opera for linux has issues with Wayland. when opera is run naively on wayland by setting ozone platform flag to auto, there is no icon and opera runs as unknown app. its been the same for a really long time and was never fixed. I mean its been the same far before opera 100 came out, I hoped they might finally fix that with opera one. Example (image) when opera on overview on gnome attached. Thank You