PO from Agreement doesn't inherit custom header DFF value

When a Purchase Order is automatically generated from a Purchase Agreement, a custom header-level descriptive flexfield (Global Segment on PO_HEADERS) keeps the value that was originally entered on the source Requisition, instead of reflecting the value configured on the Agreement itself. Screenshots of the case are attached below.

We've confirmed there is no Default Type/Derivation Value configured on the flexfield segment, and no integration involved in the automatic PO generation - so the value appears to simply be carried over as-is during document conversion (Requisition to Agreement to PO), without being refreshed from the Agreement.

Is this expected/standard behavior for header DFFs during automatic PO generation from an Agreement? Is there a supported way to have this attribute re-derive from the Agreement instead of the originating Requisition when the PO is created automatically?