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.
Flathub has verified apps. This means the build either comes directly from the developer of the app itself or someone that they approved to distribute their app through Flathub. That’s kinda the ultimate QA to me. If the developer of the app can’t be trusted then who can? Other than that, the only checks are the community.