I don't think this is the proper way to do this analysis. I believe the lemmy.world vote counts should be the same as blahaj.zone. It will still include the votes from hexbear. The only difference would be that lemmy.world's view will include the down votes from lemmy.world itself. Those won't federate over to blahaj.zone since down voting is disabled on the instance.
It should be possible to do your analysis though. It will take getting a copy of the vote history for the comments on the post. Every admin of an instance that federates with blahaj.zone has a copy of that. Then you will have to run some queries on the database to filter votes by the instance they originate from.
Now that I've looked at lemmy.world, beehaw and lemm.ee myself, you might be closer to right than I initially thought. The amount of comments in the first thread on the blocking instances, lemmy.world and beehaw, is much less than the federated instances, blahaj.zone and lemme.ee. The vote amounts on the blocking instances agree with each other and the amounts on the federated instances agree with each other.
I think that's sufficient evidence to conclude something is up. I'm going to suspect lemmy.world and beehaw filtered out hexbear comments and votes when they federated the post. This would suggest brigading from hexbear users. But I would need to view the vote database to be sure.