It's quite likely that Brave itself collects data on your usage and shares at least some of it with Palantir.
This isn't such an outrageous assumption to make here.
Telemetry can be disabled in Brave. Any kind of history/bookmark syncing is opt-in.
You're just spreading FUD unless you have evidence that Brave funnels usage data in secret.
Firefox also collects and sells data to no one really knows who.
https://github.com/mozilla/bedrock/commit/d459addab846d8144b...
There's no need to make assumptions. The source code is out there. Please, show us the relevant commits which do what you said.