Brave has native ad-block and anti finger-printing, enabled by default, and the web works excellently as in I don't know of a single site that doesn't work with it.
Firefox with Gecko is a different engine entirely and that sometimes causes compatibility issues or different behaviour, that websites have to account for.
Pretty sure that's not true. I don't see any YT adverts when using Brave, and I don't have any extensions installed.
"From what I know" is epistemologically equivalent to "For me".