Which formula have you used to map() this @mattb ?
I don’t fully get how your input JSON would look like, but if I understand it correctly you want to map the same variable name with an infinite amount of that value.
In this case, you first need to map all the arrays which are within the results array. Once you have all these arrays, you can then again map() that array to retrieve the URLs:
{{map(flatten(map(1.image_gen_results; "generated_images")); "url")}}
Hope this helps you out!
Cheers, Bjorn