Since it is a slideshow with 8 images, let’s make sure we’re talking about the same things:

The background I am referring to is the backdrop for the image, marked in green here. There is a four-color gradient in that background. It is four-color as two-color wouldn’t blend that way.
The radial gradient is inside the phone, the background for the app itself. Marked in red here, with (location of the) two colors used marked with red dots. You can tell it is radial as it goes darker in every direction around that lighter point next to the info “circled-i”. (Although, looking at the other slides again, the second color is probably that dark blue violet way at the top of the app, rather than the marked spot at the top left of this image.)
The transparent parts are the gray rectangles that have been overlaid on this background, marked with blue here.