Falkon just uses Chromiums web engine and strips everything else, they don’t use Manifest V3 as they have their own extension system (although that isn’t really mature). It comes with a built in adblocker that works fine for browsing, but youtube ads can’t be blocked. I recommend Falkon for web browsing, but I wouldn’t use it if all you want to do is watch youtube I would use a browser that supports h264ify. For browsers that do use chromiums web extension api there is a version of h264ify, which you will need for hardware acceleration.