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.
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