Maintaining a web browser is an intensely cost and time prohibitive endeavor, especially nowadays. The FOSS community can maintain a lot of things but the sheer scale of Firefox, the need for expertise, the necessary labor, it just can’t be done by volunteers and donations, at least not without using Chromium. They have to get a cash infusion from somewhere.
I don’t like it anymore than you do but ultimately the issue isn’t Mozilla, it’s the state of the technology market. Silicon Valley is no place for a non-profit organization right now, no matter how much we need it.
What we need is regulations and anti-trust, but even that may not truly save us.
They need money. That’s it. That’s the long and short of it.