The thing is that Firefox has SO MANY papercuts in this category. They all seem minor but they all represent a deal breaker for one user or another. For me it's the address bar on the bottom on mobile (ludicrous decision, whoever came up with that should leave the industry and I mean that) and their refusal to auto fill credit cards on mobile even though I know it works on desktop and I know it works in other regions.
Firefox badly needs someone who gives a shit about user experience.
In the settings on Firefox mobile, under Customize, you can choose between address bar on the top or on the bottom of the screen.
Personally I keep it at the bottom, as it's much closer to my thumbs and also the keyboard, so I don't have to adjust my hands to type in a url or search query.
I switched from Brave to Vivaldi as my second browser on Android because it's still stuck in the 2010's with it's address bar at the top with no ability to change it. The most sold phones for the last half decade have all been 5-6 inches, and unless you have gigantic hands you need to reposition your hand in order to go from typing on the keyboard to the bottom to tapping the URL bar, so I'm on the other side of the fence, very glad that they default to the bottom URL bar and actually have the option to change it to the top for those that want it.
Firefox badly needs someone who gives a shit about user experience.