Mysterious Approvers getting populated in workflow

Hello,

We have custom workflow.

Workflow has 2 steps. Review and Approval of parked document.

First PO is reviewed and if accepted by reviewer, there is one pop up to select appropriate approver and then it goes for Approval step and finally gets posted.If reviewer decides to reject the document within timeline then mail is send and workflow stops.

If reviewer rejects the document once deadline is missed, then PO selects random approver and goes for approval stage.

But ideally there is no steps/ tasks available for selecting approvers and mail notification for approval stage.

PFA workflow steps and after reviewing of parked document there is only one task to get factory deadline dates.

Anyone knows how random appover is getting selected/from where approvers are selected?

Also approve parked document belongs to BOR object DECISION and method PROCESS.