disappointing, because alternatives matter too. quad9 and other well known servers are potentially blocked by some countries, so the more lesser known services there are the better.

Mullvad talks a lot about decentralization, then hands its resolver users to one of the biggest resolvers going. Quad9 is a good operator, and they actually fought Sony in German court instead of quietly complying. They still got ordered to block. That's the problem. A blocking order only hurts as much as the resolver it lands on is used, so every operator that shuts down and sends its users to Quad9 makes the next order a better deal for whoever files it.