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.
I use the Firefox flatpak on multiple different desktops and distros and I’ve never seen this issue. All on wayland (no difference on x11 either). Weird.