I’m having the exact same issue. Not only can my app no longer reach the database, but the app itself is also very unresponsive. Both are hosted in the ams region. It may be related to this issue: App broken: could not find a good candidate within 90 attempts at load balancing. - #5 by Beaux
The weird thing is, using fly proxy works fine to connect to the database from my dev PC. So it seems the database app itself is fine, it’s just the proxy/networking between the app and the outside world seems to be broken.
I can also connect via ssh to my database app using fly ssh console --app my_database_app, but sshing to my main app gives error connecting to SSH server: connect tcp ... operation timed out.
Over ssh I ran pg_isready --host=localhost, and it says the database itself is fine and ready to accept connections.