The big question is:
Does the money go to Firefox or to funny projects and (what I consider) insane exec salaries?
The national median software developer salary is something like $110k. The middle 50% range is like $85-150k, so if you're making above 150k TC you're already in the top 1/4 of developers, who are already very high up in general.
I say this because people on HN love to pretend that "industry-standard" means $250k+ for new grads and $400k for experienced ICs when that's just not true. FAANG-level salaries (which can absolutely be 300, 400, 500k TC) are the 1% of the 1%.
I'm not sure where you're getting that number, but it's much too low.
The figures at https://www.levels.fyi/company/Mozilla/salaries/Software-Eng... better match what I saw when I worked at Mozilla.
You can compare compensation at equivalent levels for Mozilla and peer companies at https://www.levels.fyi/?compare=Mozilla,Microsoft,Apple,Goog... . You'll see that Mozilla pays well, but significantly less than them.