Almost no technical aspect of Firefox have anything to do with how much money Google pays them.
Having a quality browser is not required, merely it existing. So why waste money on novel web engine experiments when you can have AI conferences in Zambia?
You obviously haven't been following the money.
The statistical global marketshare of Firefox is very close to that of Internet Explorer --- within a single rounding digit.
https://www.bloomberg.com/news/newsletters/2023-05-05/why-go...
The most *easy* and sustainable way to achieve this is by using a fork of Firefox --- aka LibreWolf.
https://github.com/K3V1991/Disable-Firefox-Telemetry-and-Dat...
And Google won't be paying more if Firefox becomes something bigger than Chrome. Google has no interest in it. All they need is a spoiler effect.
Google knows it shouldn't be developing a browser. This paltry pocket change protects their pane of glass moat.
This is not reflected in the numbers, at least from what I've found: 300m/year in 2011[1], 400+m/year in 2020[2], 485m/year in 2025[3].
[1] https://www.computerworld.com/article/1543269/google-to-pay-...
[2] https://www.pcmag.com/news/mozilla-signs-lucrative-3-year-go...
[3] https://nerdschalk.com/85-of-mozillas-revenue-at-risk-firefo...
In the browser space, what Apple is doing is awfully manipulative of the market too. It's almost like this situation is being willfully ignored and effectively encouraged by regulators.