In that particular screenshot I believe you’re right: the one on the left is Firefox ESR while the icon on the right is whatever flatpak version available.
But I know what OP is referring to as it is a open bug currently, the DE don’t doesn’t recognize the launched instance as the pinned program due to the way Flatpak launched apps. Not an issue with Firefox in particular
Oh god. New stoves don’t have knobs? Are they touchscreens now too? I will pretend I did not just read that information and be a ‘old man yells at cloud’ when the time comes to buy a new stove.