I still blog on a server I rent but the backup is hosted in a server in my closet. I’m fully aware that rental can go away any time. And that’s been the case for decades.
Maybe it’s a generational thing but it appears people assume these platforms owe them something. The TOS makes it clear they owe them very little. So you can be muted, banned or deleted at any moment.
I’ve watched many social networks disappear and end up in the footnotes of a Wikipedia article. Nothing about the internet is guaranteed nor permanent. Twitter nor Mastodon owe you anything.
But generally it takes a lot to get banned by most fediverse instances. You basically either need to be a nazi or consort with nazis.
There are, of course, instances that would ban you for less than that, but these tend to be much smaller and trying to foster a very specific type of community. If they'd ban you, they probably wouldn't follow you either.
The solution to this is to move to an instance which hasn't defederated from the one you're on. Worst case, setting up your own.
It works by the old and new server "cooperating", so it won't let you move between two servers which won't federate with each other - in that specific scenario you'll need to go via a third server which both speak to.
The move appears to you as if your followers unfollows your old account and follows the new account, so they're all "redirected" to your new handle. E.g. you can see that here: https://mastodon.social/@vidarh
You indicate to the old server where you want to move to, and then to the new server where you're moving from, and the fact the old server will specify your new handle in your profile is used as proof when informing your followers instances of the new address.
If you do this, you can see mastodon.social returns a "movedTo" attribute for my old account:
curl -H "Accept: application/activity+json" https://mastodon.social/users/vidarh | jq .movedTo