Firefox on Android is just not good enough. Mostly slow and glitchy, last time I checked a few months ago. And at least one website wouldn't load the mobile version properly.
In fact, I'm still struggling to find a really good browser for mobile.
Been using Firefox for Android for last couple of years and it has been great! Been using it exclusively on a OnePlus 7T and Samsung S21FE. You should really try it again. Extension support is icing on the cake.
I use Firefox (librewolf) on desktop and Brave on mobile, its privacy respecting (with the right options) and has a quite a few things built in to block ads and trackers