Libtewolf is hopefully there. Ublock origin is pre-installed

Librewolf, like all the forks, free-rides on the upstream work of paid Mozilla staff in order to be secure. It's a band-aid, not a solution.

But perhaps the existence of the forks tells the Mozilla management something?

WebKit (as used by Safari) was a fork of kHTML (written by the KDE team). And Google forked WebKit. Now we have dozens of Blink forks including Microsoft’s own browser: Blink.

I think it’s pretty safe to assume that forking the code is a low incentive for change

Band-aids like this have existed for many years, plenty of time for Mozilla to listen. And in all that time, they never had the idea to make the band-aids redundant.

I'm using Waterfox on desktop at the moment, but I really wish Mozilla would get their act back together and make all the forks unnecessary. I'm not saying they need to die: I only hope one day they aren't needed anymore.

Also, I'm afraid that's not sustainable in the long run. How long before Mozilla makes a change so big to introduce some nasty feature that it becomes impossible for forks to stay up to date with upstream? Do they really have the resources necessary to maintain an actual fork and not just a customized version?

Of all the forks I think Waterfox is the one with the strongest case that they can continue on even if they have to fully decouple from Mozilla Firefox.