This is a follow up to bug #249872. Opening https://dor.mo.gov/forms/MO-1040%20Instructions_2022.pdf and attempt to download it using the PDF.js UI. It won't work: [Error] Refused to load blob:webkit-pdfjs-viewer://pdfjs/39176f55-4f67-4515-9733-dc0f6d764506 because it does not appear in the frame-src directive of the Content Security Policy.
<rdar://problem/126863829>
It's probably related to https://bugs.webkit.org/show_bug.cgi?id=264355