The structure of Brave extensions are quite different from the mainstream Chromium format (like QupZilla), allowing you to steer clear of the mess that is Chrome Webstore, but also making it harder to find an extension you're looking for. These extensions (at least the active ones) are in the path brave/[appversion]/resources/extensions/. For example, the torrent one has a background HTML page with .properties, .js and image file references.
That said, I'm not liking that browser much. The GUI is pretty and that's it. I prefer the QZ way (changing the architecture, yet making it feasible to develop or download new extensions and documenting how to do that). Brave just completely sacrifices customizability on the altar of "security" and "privacy". Yes, we're all on a security forum, so some people will completely disagree with me, but I think that's too much.
I appreciate their honesty in 'fessing up to replacing ads with their own. Ads aren't necessarily a bad thing, but I'm wary of these practices as a lot of software that started with "innocuous" advertising have ended up as bloated bags of trackers and annoying ads not much later.