Its biggest and most well-known app is Mastodon, the microblogging platform that Meta’s Threads is currently in the process of interconnecting with (via ActivityPub).
Meta is trying to interconnect with Mastodon? Fuck all that, I’ll delete Mastodon before I interact with anything Meta.
Meta is trying to interconnect with every Fediverse app; Threads isn't specific to Mastodon. Mastodon is just shorthand for the fediverse as a whole since it's the dominant platform.
“Mastodon” is essentially a front end application for ActivityPub. Nobody controls “Mastodon” other than the developers who can’t control who federates from whom.
“Deleting Mastodon” isn’t going to help you, instead see if your instance is a member of Fedipact. If your instance shows in the list as blocked or limited, then you are fine