This is entirely driven by a simple fact that in ad-supported businesses users are not the same as the customers.
I advocated several times and will do it again - Firefox should completely embrace a freemium browser business model, align incentives with its users, and attempt to have a second golden age (first was 2005-2010).
IMO open source works best as a community implementing small, single-purpose programs, which the users can integrate however they’d like. Web browsers have gotten too monolithic and the internet has gotten too over-complicated for a healthy open source web browser to exist.