[jhoechtl]

I know about

GDK_BACKEND=wayland firefox

That works on Gnome and sway, not on plasma. Intel GPU. Still open bugs on bugs.kde.org

[pedrocr]

I believe the correct variable these days is:

MOZ_ENABLE_WAYLAND=1 firefox

This makes firefox a full wayland app. But I only use sway, so maybe there are KDE specific bugs.