Figma doesn’t keep the original file names for image fills in the UI. However, there used to be a workaround for by getting the file name in Inspect > CSS code in background property.
As recently, Figma stopped showing original image filenames even in the generated CSS code, I was looking into API to see if the original image names are preserved anywhere. I couldn’t find the original filename on any of the endpoint JSON.
Perhaps I’m missing something or is this info isn’t anywhere in the API?