The change have been pushed in few commits beginning with 66c21a2f65eb0466806090746acb58190f1ac716. SQLExecDirect now uses text protocol and client side prepared statements(CSPS). That can be switched to use of binary protocol and server side prepared statement(SSPS) if necessary(for example for CALL statement).
SQLPrepare uses by default SSPS, but it can be switched to CSPS, for example in case of multistatement query.
The option to also use CSPS by default in SQLPrepare has been added, its name is PREPONCLIENT. In some case it will be automatically switched to SSPS - one of cases of request of metadata before SQLExecute call.