I still occasionally slip on that myself. It’s the first non-Microsoft office suite I used and it’s burned into my memory.

This is amusing, but one guy from the crosspost raised a valid problem:
If the hexbear domain fully dies, then all the idiots kept in containment by defederation will start jumping ship to other instances, and start causing trouble for users and moderators.

There is a procedure for migrating profiles and posts to new instances, if the old instance is still up.

And on the admin side, there’s established time frames and grace periods for server closures. Barring a big disaster, you’ll have time to move your stuff.