BUG - Guided Journey background image on Supplier Registration pages trigger authentication

Organization Name (Required - If you are an Oracle Partner, please provide the organization you are logging the idea on behalf of):

Public Health Agency

Description (Required):

We have a background image on our Journey which we use on the Supplier Registration portal:

However, the background image doesn't load to Suppliers. Instead, it triggers an authentication mechanism, which is visible in the web developer network trace:

Basically, the browser tries to load the background image, which triggers an authentication request to the browser and it pops up as a basic login box. In this example we have two images so the flow is called twice.