Running any given set of repl/sharding jsTests on 4.4 and 5.0 has a difference in the amount of information-level logs emitted when a connection is closed.
This behavior can quickly swamp the log – in a given jsTest, I see an average of 200 connection ended logs (mostly due to the hello command*). On top of this, the server triage team has concerns that the "terminating session due to error" message will scare users who are trying to upgrade from 4.4 to 5.0 (HELP-25086).
This ticket is aimed to suppress these extra logs if possible, and change them to debug level.
*This was verified by adding printStackTrace to the lowest-level of these messages, and the vast majority of these messages were coming from a connection being closed while the recipient side of a hello command was waiting in ReplicationCoordinator::awaitHelloResponse