How to fix garbled Media previews for external PDF files?

Hi all,

I have Media items that point directly to PDF files in external websites, and this is resulting in a garbled preview, like this one below.

I get that that it is just rendering the contents of the PDF file, but I would have expected that it would detect that I was linking to a file that was not text and that at the very least no preview would be rendered.

 Are there any options to fix this?

Thanks.