Invoice Approval Allowed Even Though WF is Turned On

Summary: We have created a Workflow for all contract invoices that have a credit amount to be routed to a specific person.

Content (required): The Work Flow rule is working. The notification is sent to that person and states the Approval has been assigned to them. However anyone who has access to the Invoice overview form can click the "Approve" and Release Buttons with no errors.

How to we prevent other people from approving the credit invoices?

Version (include the version you are using, if applicable): 21C

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