Supply Chain Financial Orchestration- I/c AP invoice approval showing auto workflow approve?

Supply Chain Financial Orchestration- I/c AP invoice approval showing auto workflow approve? - In the case of a Transfer Order-based Intercompany AP invoice, we can see that a payable invoice has been created and workflow-approved. However, since this is a non-PO invoice and no invoice approval rules are defined for the Business Unit, how is the approval process functioning?