IMHO the EU should step in. Having a browser that is not controlled by big tech should be part of an effort to reduce the dependency on the US.
How about not involving governments in how Firefox is run. Especially not those keen on backdoors and "Chat control". It could be a stand alone association ruled by its members or a classic free-for-all whatever goes code talks FOSS project.
Mozilla has been less and less dependent on Google and is now working on a VPN, MDN Plus, and other revenue streams that are also helping it become more independent. But the truth is that if all Google money suddenly stopped today, there would be no more Mozilla