Oracle fusion - Purchasing document approval - for change order action is not working properly

We have setup our purchasing document approval only for change order , where at header hierarchy level , we have setup job level approval hierarchy

based on amount slabs and in action , the start point of approval is setup as requester.

Our understanding is if there is a change in the purchase order, then it will follow requisition's requester's manager hierarchy, but we have noticed if amount slab is getting changed, in that case, workflow is starting from initiator. Can someone please confirm if system is behaving correctly? Ort something wrong with system?