That is wrong, not everything is public on the Fediverse. Usually the content which is published with the Public namespace as a recipient is public, the rest o

That is wrong, not everything is public on the Fediverse. Usually the content which is published with the Public namespace as a recipient is public, the rest of the activities are only disseminated to just the recipient's and author's servers. There might be bad actors, or badly implemented software which don't do that, but the Fediverse is composed of more than just Mastodon.