Backdrop filters on transparent SVGs

Hey! Does anybody know why the Backdrop filter doesn’t work with transparent SVGs? Without custom code that is…

They mention it is possible on the Webflow University:

“You can add backdrop filters to any element in your design. However, to be able to see the effect, you’ll need to make sure your element’s content is partially transparent. You can do this by using SVG or PNG image files, setting a transparent background on the element, or reducing the element’s opacity.”