@Maholmire Can you show me an example of that? Because the fediverse does not federate with twitter. Twitter has nothing as of now to federate this instances as well.
I'm assuming you might be talking about crossposters, which is what people use when they want all the content they post on a website to be posted on another. There are people that only join fedi to set up a crossposter for their twitter account, meaning that their content is mirrored on fedi but they never really check it. A good example of that is the one from the European Commission, where they crosspost everything on their fediverse instance but never check it :^) https://social.network.europa.eu/@EU_Commission

When you see something like @/user@twitter.com it's most likely because they're using a crossposter and therefore, are posting from twitter instead