I'm not sure there is an alternative. It's not just Firefox: other big projects like this already have foundations and lots of money in funding, but then spend the money on things not at all related to the core mission.
From what I've read, Mozilla won't even take your money to develop Firefox. They'll instead use it for the Mozilla foundation which funds a bunch of social causes.
Wikipedia has a huge endowment, so they really don't need money to keep the lights on, but if you donate, it'll similarly be used for funding social causes through the Wikimedia Foundation.
There's also a Linux Foundation for funding Linux-related stuff, but here again a lot of it is spent on social causes, not directly on development-related costs.
You'd think that if funding were really that tight, social causes would be cut and just keeping the servers running and essential personnel employed would be the highest priority, with SW maintenance and development a close 2nd. So, apparently, money must not be that tight. Or, if it is, it's being woefully mismanaged. But I think there's more to it: it seems like when times are too good (something gets popular and gets funding), then the people in charge expand the scope of the project to consume all the funding, adding on various pet projects (like those social causes), instead of saving the money in case of a funding downturn later. Wikipedia probably did it best by setting up an endowment so that everything else is just gravy, but even here they're constantly asking for more money on the site and acting like they really need it when they don't.
As much as I disagree with Ayn Rand on a lot of things, she did make an important observation.
Parasites will be attracted to high value things in order to extract value, not to add to it. They climb the hierarchy of the organisation and then use it for their own benefit.
It is not only developers who do resume building oriented work. These people start social causes so that they can claim that they spearheaded this or that campaign. In order to gain prestige.
Engineers who only care about the product become the bottom of the hierarchy and the organisation becomes a reflection of the needs and wants of these parasites.
From donations and government grants. You know, like proper non-profits that aren't trying to LARP as a SV unicorn.
All sorts of "experiments", normandy, telemetry, pocket, looking glass, all sorts of phoning back them or either google... so many things to name. And now this garbage to add to the list.
You have to do so much work in about:config to clean this up and i'm not sure if it can be fully.
Extremely scummy organisation.