I have been suffering from the same all day.
At one point today I was getting near-constant
2023-10-17T16:02:50.830 app[****************] ord [info] 16:02:50.829 [error] Postgrex.Protocol (#PID<0.1998.0>) failed to connect: ** (DBConnection.ConnectionError) tcp recv (idle): closed
2023-10-17T16:02:51.929 app[****************] ord [info] 16:02:51.928 [error] Postgrex.Protocol (#PID<0.1993.0>) timed out because it was handshaking for longer than 15000ms
errors returned from the app (I was able to connect to the db from outside the app just fine throughout). I restarted the DB machine and that went away but the app is still very slow.
I also have the can’t deploy problem as detailed here. Unable to deploy due to builder 500 error
Like you, no changes at our end to the app prior to this starting.