Unfortunatly this wasn't Android exclusive. The Firefox Android App sucked ass in the past and will probably suck ass for the foreseeable future. There are currently multiple support and Reddit threads going about insane battery drain and heat build-up caused by the Firefox App (even when suspended and battery optimized). The UI is barebones and lacks basic features like closing tabs from the navigation bar or opening new tabs by scrolling left on the rightmost tab. Even something as simple as having actual tabs akin to the desktop version is not present, instead you have a tab list or grid view that barely manages to load previews for each open website. The native video player also hasn't been touched in a literal decade.

All in all Firefox Android is a horrible experience that has only the ability to use extensions going for it.