Only insofar as some instances block communication from some other instances. Not mine though, that’s actually one of the reasons I picked it. That and it being by an org that’s older than the web and runs a public unix server and a bunch of retrocomputing type services as well as fediverse stuff. They started out as a dialup anime BBS.
Are they? It literally points out “Who you voted for is secret” on the ad, right above where it says that people will know if you voted.