I don't think it's the same source code (uBOL vs uBO). And it's definitely not the same logic, that's the whole point, blocking with MV3 must be done in a declarative way.
Yes but that's not the same. Because of Chrome limitation it can't update it's blocklist directly. You have to update the whole extension to update the blocklist and that goes through Google validation in the Chrome store. It adds delay and Google could even refuse some updates. The blocklist is also shorter because not all filter rules are supported.
You are right that there are underlying causes that needs to be addressed. That's why it spread so much and so fast. But that doesn't make racially motivated fake news OK.
But this seems easy to automatically block, no? If a client is querying an unknown domain check for some Matrix related data in /.well-known/ and add it to the block list if there is. And since the servers are publicly advertising the port used you just need to periodically check the list of known matrix domains you are creating in the first step.
Russia is already doing DPI and blocking ESNI so that seems easy. A more widespread usage of ECH would help everyone, as is Signal advocating, but that's not the case yet.
I don't think it's the same source code (uBOL vs uBO). And it's definitely not the same logic, that's the whole point, blocking with MV3 must be done in a declarative way.