community/firefox: asks to be set as default browser on every startup on KDE Plasma

Even if I tell it that it's allowed, it never actually sets itself as the default so just asks again at next startup.

I know I can stop it from asking entirely in it's settings, but I rather have it fixed so it actually knows how to set itself as the default.

Might this be DE related? I'm using KDE, not sure if it applies on GNOME as well.