To be clear, the difference between the NFL (when it was a 501(c)(6)) and Mozilla as a 501(c)(3) is the former tax status specifies an entity's purpose as serving members of an association, while 501(c)(3)s have a purpose to serve the public good.
Strictly from a nonprofit financial perspective and from reviewing its most recently filed public 990, Mozilla doesn't pay its senior staff an exorbitant amount; it looks to be an entity with $20-$30M in revenue and double that in assets, so seeing its highest paid employees making $200-$300K isn't out of the ordinary. It does look to pay quite a bit to Upwork, which I assume is their rent expense. It can be difficult to tell from a 990 if there is fraud going on however.
Strictly from a nonprofit financial perspective and from reviewing its most recently filed public 990, Mozilla doesn't pay its senior staff an exorbitant amount; it looks to be an entity with $20-$30M in revenue and double that in assets, so seeing its highest paid employees making $200-$300K isn't out of the ordinary. It does look to pay quite a bit to Upwork, which I assume is their rent expense. It can be difficult to tell from a 990 if there is fraud going on however.