Isn't the majority of Mozilla's revenue from Google's paid placement as the default search engine? Or has this changed in recent years?
Quick googling confirms 50%+ of revenue came from Google 5-10 years ago, but couldn't find more recent data.
If Google is Mozilla's primary revenue source (especially if it's the majority), then Google effectively controls Mozilla via the leverage it has to pull Mozilla's largest revenue source.
Edit: Also raises the question, what company or organization should be developing browsers? A browser is something everyone expects to be free, but a browser is by no means free to develop, operate and maintain. For-profit browser companies (like Brave) would be forced to monetize the browser (like Brave tried to do with BAT crypto tokens, ads on the new tab page, etc)