Why PO release were created automatic after summited "Workflow Background Process: POAPPRV, , , Y, Y

Action : Summited "Workflow Background Process: POAPPRV, , , Y, Y,"  (It's not normal process. I want to run it for updating status of one PO, but I found other effect that PO release were created automatic )

Result : Unexpected behavior. New release were created automatic from BPA (one release per BPA for around 25 BPAs )

Steps to reproduce

Step 1-2 are normal processes, and I guest that it may related step3
1. Create PR to Sourcing RFQ with blanket purchase order type (it is normal process )
2. Create Souring to PO blanket (it is normal process)

3. Run concurrent "Workflow Background Process" with parameter (it is not normal process, run and found this case)