What I did before:

I disabled KDE Wallet and kept Seahorse enabled.

I completely removed KDE Plasma and reinstalled it.

@RockyPlantchair-0

Have you done the procedures here?

https://github.com/Ld-Hagen/fix-opera-linux-ffmpeg-widevine

I am using a Debian/Ubuntu-based Linux distribution (Pardus).
When I use the Opera browser on the Gnome desktop, everything works fine. However, when I switch to a KDE Plasma session, the Opera browser forgets my credentials and asks me to log in again. When I switch back to the Gnome desktop, I see that my session there has also been terminated.