Its even worse when you force Firefox to use wayland its icon doesn’t even show.
Edit: Oh since everyone now is confused; I only have the flatpak version of Firefox installed yet it doesn’t use the pinned icon and doesn’t even use the firefox icon under wayland at all.
Yesterday I freed up 6GB of diskspace by uninstalling a single flatpak app and running
flatpak uninstall --unused
Somehow flatpak had grown to fill the disk over the years, my installation is about 5 years old, and I have only used flatpak very sparingly.