And this is one of the many reasons I don't donate to Firefox. Firefox employees should really fork that project and make it better than what it is now instead of just being Google's dog + an excuse to pay millions to a single person and hundreds of thousands to random individuals, who have nothing to do with Firefox.
400M in cash could go to a lot of development efforts. They could rewrite Firefox entirely in Rust, make it run on any platform, move the needle on web technologies in a big way, hell, they could make their own damn phone with that kind of money, or even write their own competitor to ChromeOS.