Hi,
It sounds like someone else is having the same issue:
The reply from Fly in that thread says that restarting should help. However you say it doesn’t 
Given that … do you see any more info if you look at the status of that individual vm’s id you list above? e.g fly vm status 148e392f724438 ? I wonder if that reveals e.g any out of memory error or something to work with.
If not, can you get at a private IP for the vm? Like if you run fly ips private -a clasfle-db … does that reveal it having one? If it does have a private IPv6, can you connect to that (don’t reveal it in here)? e.g fly ssh console "long-ip-v6-here"
If you can SSH in to the vm, I wonder if you would then be able to at least get at the data on it e.g the mounted volume? I’ve not tried doing that with a postgres vm so it’s a total guess I’m afraid.