That's my exact issue with Brave - though I do like what they're aiming for despite being in the ad-tech business.

I don't think it's the browser's role to police such things, it should be a dumb agent only requesting content, displaying it and not leaking any sensitive stuff.

I believe the way forward is to have another 3rd party where you can manage those things. Want to create one persona per category of website you visit?

Even go as far as one per website? Doesn't matter, your metadata, you own it and more importantly your browser stays out of that business.