It would seem that the Brave browser and Firefox share similar goals on privacy. It’s hard to navigate the differences in their perspectives on this, why would one choose one of these browsers over the other if concerned about online tracking?
Brave still contributes to a chrome monoculture, and it still shows ads, so it has a different vision of privacy.
That they figured out a way to still offer advertising despite this restriction, that’s just an orthogonal feature that doesn’t affect the stance of privacy.