https://en.wikipedia.org/api/rest_v1/page/media/tangent
is missing the images for the formulas embedded in the article, for example:
https://wikimedia.org/api/rest_v1/media/math/render/svg/3c924ec6626c572300b256a28bbb285cc98fe040
On iOS, we cached those images when the user saves the article, so that the full article with formulas is available offline. It'd be ideal if they were added to the items list, and items were given a property to indicate whether or not the image should be included in the fullscreen image gallery (these images would have that property set to false)