I have been using Firefox for over 10 years now, and if they do something stupid I'll be on here complaining with everyone else. If they crossed the line I would definitely look for another browser.
The problem with Brave users seems to be that Brave can do no wrong. Bundling crypto in a browser seems absolutely insane to me. Remember all the shit Firefox got for bundling Pocket? Difference is, Pocket actually makes a little bit of sense in the context of a browser.
At the end of the day, it's thin veneer over Chromium and IMO they won't be able to block manifest v3 forever. Firefox can.