Icons on macOS Big Sur are still the old ones. So far, only the Mozilla products (firefox/thunderbird) haven't updated macOS icons.
not sure why at this point.
not sure why at this point.
And you still have to manually configure Firefox to use the native full-screen-api so you can use the macOS menubar to chance your volume. Horrible, just horrible ...
But I'm currently on Firefox Nightly and pretty happy about the recent UX/UI changes.