When we update the username for the rehired employee under Review New Hire Data, the updated name is not getting saved. It returns to the previous name after saving the data.
Username update is not supported in New hire data review step and this has been logged for this as an enhancement.
Given that this is an enhancement, kindly track this via a post on the SAP Influence portal.
Rehire Username , KBA , LOD-SF-OBX-RHM , Rehire Mechanism , Product Enhancement