Well that is because Brave has been doing it longer, and Vivaldi only has about 30 devs across all the platforms, which is a fraction of Brave, although Brave has its issues as well, just not in the adblock department. I have found that if you use the uBlock block lists it is most of the way there, but it is not ready yet and I think that Vivaldi will have to consider picking up some dedicated devs. Also it is a ‘Vivaldi Thing’ to launch things piece mail and get those pieces working fully before adding on the rest of it. Then over time it gets good. But Vivaldi has come a LONG way when it comes to aggressive adblock detection.
That being said right now YouTube is detecting it and it is dumping the most manpower and money into this. When it does work you can pretty much use it across the web and the few cases that it doesn’t work usually OK just to pause it for a while and you won’t get too many ads.
However if Mv3 comes out and they haven’t gotten their act together I am going to Firefox or Brave, as much as I don’t like how they do business. Then there will be the Google Search thing running through the courts and we will see how Fx and Br come out and change their model.
Even Tommy Douglas thought that the mice would elect cats. https://www.youtube.com/watch?v=GqgOvzUeiAA