PreparedStatement have a specific implementation for failover, since the concept is to send only data after a "prepare" has been done.
When this is used on a slave connection and a failover happen, if the master connection is up, prepare will be done on master to have no interruption and avoid forcing immediatly a reconnection to a slave to avoid a bottleneck that can even lead to JVM crash.

When a slave connection is recovered, the next execution has to use this slave connection, to avoid long running preparedStatement using master for too long