Not lost, but inactive / isolated. As I understand it, when a user on insurance A subscribes to a community, votes, or comments on a community on instance B, that content is copied to insurance A and the two instances will sync their changes together. If instance B shuts down or the two instances defederate, then the content on instance A stays intact, but it no longer syncs with the source of truth.
Is each instance like another person with a server?
Yeah. I would assume that most, if not all, open instances are going through a 3rd party hosting service, but nothing stopping them from being hosted on hardware in somebodies home.
Could that person just shut it down whenever they wanted to?
Yup. Anytime and for any reason. It might cause a moment of disruption, but the beauty of federation is that you can always setup an account on a new instance or create your own.
Are there any companies that have invested in hosting Lemmy/ other fediverse servers?
Yes. The only one I can think of off the top of my head is Facebook federating their Threads services. I’m sure that there are others.
Somebody please correct me if I am wrong, but didn’t the United States invade Iraq despite the objections of the UN Security Council? That happened, right? Without reprocutions?
If that’s the case, I’m wondering who cares about the UN objecting to laws a country passes, within their own borders, that are not human rights violations. What are they going to do? Write a stern letter?
Yes, but they would be separate accounts (comments, subscribed y communities, messages, etc). I have an account on lemm.ee and lemmy.world which I actively use. It can get a bit annoying making sure that I stay subscribed to the same communities on both, but it’s also nice to get different feeds.
Another option would be to stand up your own closed instance, so your account is the only one. That way storage and bandwidth should be minimal enough that you can host at home and also have full control over settings on your instance.