Firefox has never put a priority on privacy. Just take a glance at their privacy policy. And it's plain to see that they are moving further away from it every day.
There are a dozen Firefox forks though. Mulch, DDG, TOR, Fennic, Bromite, etc.
Functional like mull? Oh wait. It has been shut down.
If it works, it works. Havent had any problem with firefox. So i stick with it. I dont have time pondering what browser to use every single time stuff like this happens.
There was the time when Daniel Micay was the project lead and I wouldn't trust him either.
The current leadership seems fine though. I dislike that they only want to support Pixel phones but other than that I don't see any issues.
I use Iceraven currently. It's a Firefox fork. Back when I started to use it, It was one of only two browsers (other being Smart Cookie Web Preview) to support extension sideloading on Android.
I don't think Iceraven is as hardened as Mull, but it is updated on a regular basis. Either case, for most folks, regular Firefox should do the trick. There is also Waterfox, another FF fork on desktop/mobile but it hardly has much to distinguish itself.
@Blaze I'm using FOSS Browser since a long time. I want to keep things minimal on my phone and this one is using my phone's WebView, so it takes less space. There are some drawbacks for sure with this one, but I can cope with them.
Currently I'm using Chromite (added some more blocklists),
Fennac (hardened as much as I can),
and Brave ( I known I known. I only use it when some website just don't work)