How do I export an image of a screen from prototype mode?

So I have this overlay screen in my prototype, how can I export an image of this specific screen of the overlay?

In my figma file I have the screen set up with the overlay as a separate frame from the actual page so i dont know how to export the screen with the overlay there

I do not believe you can export an image from the prototype within Figma.

But you can create a copy of the frame and add a rectangle with black fill and a 20% fill opacity for example on top, then add your top sheet. After that you can export the image of the frame from Figma design file.