There are many valid counterpoints on why you shouldn't trust/use this, but the mere existence of it raises a very valid point and calls Mozilla's BS; why does this fork exist at all if Mozilla supposedly cares about your privacy, security and freedom?
Mozilla doesn't actually care that much about privacy or freedom, it's just marketing to make line go up and to the right while Mozilla staff can keep collecting paychecks for being "the good guys". There's a lot of money involved.
There is a big disconnect between what they say and what they do.
They're not an ad company, so Google/Chrome is obviously worse, but if you care about privacy you don't ship a browser with surveillance features in it (which is what Firefox is).
I am happy this project exists, and I will support them. This is how free software is supposed to work.