They setting themselves up for a major GDPR suit, as well other lawsuits for violating privacy policies of other services that never opted in.

I wonder if there’s a way to fuck with the info that is sent to Facebook in some way from instances, kind of like an obfuscation method. So instead of us defederating, we force them to due to spamming their fetched content with nonsense.

If you look at your profile from another instance, your user history there will only contain stuff that that instance is federated with. Users looking at your profile wont see comments and posts you've made onto communities that aren't federated onto the instance they are looking at your profile from.

One comment onto an instance that federates with threads would leak that one comment, not your entire user account's worth of data.

It's still bullshit.

Yup; you’ll have to start watching where you post and only post on servers that don’t federate with Meta.

They would would have to scrape through a custom means like a web crawler. If you're defederated from them, content your instances won't be sent to them via other instances.

They already can and do scrape literally every website. If you're putting data on the internet thousands of different companies and governments are collecting it.

As far as I understand federation, you should be OK as long as you don't interact with instances that are federated with meta garbage. Blocking an instance is one click but it'll hide comments from their users and make you click a button to read them. Its not that big a deal though

I don't know if interacting with users of those federated instances would be safe or not, but your exposure I assume would be limited to whatever you reply to them.