It's not clear what this claim is based on. Most of its money? Firefox is an excellent browser, and probably much less funded than Chrome/Safari.
They are focusing on things that are nothing to do with their core product, and have been acting so for a long time.
Mozilla is deeply unhealthy, and has been slowly collapsing for more than a decade at this point. I believe that the significant majority of its staff are doing things of no or negative value to Firefox.
I suspect that ten developers not beholden to Mozilla but with a mandate to make a good browser would be better custodians of Firefox. If you raised the budget to forty, I’m all but certain of it.