Meta announced that users on Threads will be able to see fediverse replies on other posts besides their own. In addition, posts that originated through the Threads API, like those created via third-party apps and scheduling services, will now be syndicated to the fediverse.
I’d hope it’s carefulness but it doesn’t seem like it. Facebook should want to destroy fediverse instances (from a business point of view), they are supposed to be a monopoly and the fediverse is their biggest competitor.
Only time will tell. They’ve definitely done their own share of EEE like for a while you could use Facebook Messenger over XMPP then closed it down.