Brave and Vivaldi have ad-blocking included because they offer an alternative advertising scheme (replacing ads with their ads). From a broader perspective, it is a silly situation. Like hiking with a thief who steals from everyone else (other ad-companies and websites you visit), but promises not to steal from you when you disable 'companion stealing'Why would anyone switch from the Brave browser..
It is possible though, my father used to race with homing pigeons. When my mother found a little kitten left alone in the country side and took it home, my father promised my mother to kill the damn cat when it would touch one of his racing pidgeons. That kitten grew up to an unusual large tomcat and occasionally came home with rabits and wood pigeoon's but it never touched my father's racing pidgeons. The cat even chased other cats away when they showed interest in my father's pidgeons. It had a happy long life.
So as long as it purrs on your laptop and bytes others you are fine I guess.