"no one really knows who" is probably also Palantir or someone who resells to Palantir.

Well Thiel investing in Brave once at the beginning doesn't necessarily mean that Palantir is getting any data now (even though it's presented as if it was a fact in other comments here). It's probable, but really it's just speculation, just like anyone can speculate about who's getting data from Firefox.

But at least with Brave, the initial funding information was made public, so there's already more information available to users in comparison with Mozilla. Mozilla just said: "there are a number of places where we collect and share some data with our partners" - that could mean literally anyone.