There is a field with a unique data key, but the field name is intentionally set to a single space (i.e., it should appear as though the field has no visible name). This works correctly in both the Portal and the FenX UI.
However, when attempting to link a company entity to a portal account, the user can still see this field and its default value as one of the searchable fields on the “Link” page.
Solution:
The field was indexed in the backend and had an order value of 1, which caused the system to treat it as a valid ordered field and display it in the UI. After removing the order and republishing the policy, the field no longer appears on the Portal link page.