Unlike other reply, I do not work at Brave, and I can also confirm that Brave never did that. They do have their own ads but those have always been opt in (you are not opted in by default), and they do pay some small amount of USD in their crypto token for opting in to those - it's pennies. People scoff at the pennies but guess who pays out nothing to show you ads against your will - literally everyone else.

What you may be thinking of was at one point, when you went to a URL (for some URLs), the browser would rewrite the URL to contain their affiliate link. There was blowback for doing that. They quickly removed that/haven't done it since as far as I know