This monitor rolls up the data synchronization state of all database replica in the availability replica. The monitor is in unhealthy state when any database replica is not in the expected data synchronization state. The monitor is healthy otherwise.
At least one availability database on this availability replica has an unhealthy data synchronization state. If this is an asynchronous-commit availability replica, all availability databases should be in the SYNCHRONIZING state. If this is a synchronous-commit availability replica, all availability databases should be in the SYNCHRONIZED state.
Find the database replica with unhealthy data synchronization state using database replica monitor and resolve the issue at the database replica.