How to use Facebook's official API to determine if an ad is in its learning phase

We can see the Delivery field on Facebook's ad placement interface to determine whether the ad is in Active, Learning limited, or Learning status. How can we use the official API to retrieve this field?

I have read the corresponding official documentation. but I couldn't find the corresponding field in it. https://developers.facebook.com/docs/marketing-api/reference/adgroup#overview