Confirmed Quantity changed/Order quantity in sales units changed

Dears,

When a complaint transaction is released in SAP CRM system, it also generates a return SO in ECC, however for a particular product the quantity in ECC is automatically reduced, this is the case

Complaint Transaction > Quantity in CRM for Product A = 4
Return Sales Order> Quantity in ECC for Product B = 1

The quantity is automatically changed by the user ERP2CRM(basically the system is automatically). Please see the screenshot

Kindly advise what could be the reason for this.