A growing number of instances (mainly of Mastodon so far) are signing an ‘Anti-Meta Fedi Pact’, pledging to block any instance owned by Meta in the fediverse.
I don’t know how big this will get or how effective it will be, but if you run a fediverse instance, you should take a look at this https://fedipact.online/
There’s nothing stopping them from setting up a stealth instance and doing this now, right? Who’s to say any instance isn’t already being run by Facebook for data mining?