I'd like to remind that when you publish a post on Mastodon, it will not only be federated to other Mastodon instances or to the ActivityPub-verse - it will also be accessible and possibly boosted to other networks through Friendica and Hubzilla and both have predated the release of Mastodon #BridgyFed #BlueSky #Mastodon #GDPR #privacy #bridge #proxy #mirror #consent #federation https://github.com/snarfed/bridgy-fed/issues/835

Opt-out is a terrible default and should be reconsidered