BU available in Requisitioning BU dropdown even though user doesn't have access to the BU

Summary:

We have 2 Business Units A (Procurement BU) and B (Procurement and Financial BU).

User has access to BU A and is also a procurement agent for BU A.
BU A is a service provider BU for BU B.

When we create a Purchase Order and select BU A, under Requisitioning BU dropdown, it also shows BU B, but user doesn't have any access to BU B. How can we not make it appear in our list?


Content (please ensure you mask any confidential information):

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):