For real though, if it bothers you that much, I think it’s possible to change the shortcut icon on your desktop. You would have to download the old Firefox logo as an image on your computer, and then edit the properties of the Firefox shortcut to use the downloaded image of the old icon instead of the regular app icon. This won’t help for the mobile app though.
Look how they massacred my boy…
For real though, if it bothers you that much, I think it’s possible to change the shortcut icon on your desktop. You would have to download the old Firefox logo as an image on your computer, and then edit the properties of the Firefox shortcut to use the downloaded image of the old icon instead of the regular app icon. This won’t help for the mobile app though.
Mobile app can be changed with viral or some such icon downloader, assuming you're on android.
Depending on your launcher it can be even easier. I use the Firefox logo on Mull (Firefox fork from F-Droid) to make it easier to find