DM Open API background-color parameter is not working as expected

The DMwOA implementation has a background-color parameter but it doesn’t appear to work. What do you need to do to see it in action?

Description description

Description : We would like to use the background-color parameter provided by the DMOpen API -ref
https://developer.adobe.com/experience-cloud/experience-manager-apis/api/stable/assets/delivery/#operation/getAssetSeoFormat

However the parameter when applied does not render any change to the image

Resolution resolution

Here an image on a test instance that has an alpha channel for transparency:
https://delivery-p12168-e1686215.adobeaemcloud.com/adobe/assets/urn:aaid:aem:44a89e06-2da7-4026-8180-d6bf0efde6d7/as/Backpack_vert.png?width=1024&quality=65

I need to request it in jpg in order to have the tranparent background
turned into the background color, and then also specify to turn off
auto-formating.

Here is the background-color parameter at work:
https://delivery-p12168-e1686215.adobeaemcloud.com/adobe/assets/urn:aaid:aem:44a89e06-2da7-4026-8180-d6bf0efde6d7/as/Backpack_vert.jpg?auto-format=false&width=1024&quality=65&background-color=rgb,00ff00