Why are some PDFs scrambled when opened with Preview on Mac?

The PDF does seem to display incorrectly on Catalina, but not on other versions of macOS.

Preflighting the PDF in Acrobat flags several instances of fonts that are not embedded. Acrobat and other versions of macOS seem to be able to substitute the system Arial and Times New Roman, but Catalina does not. I'd suggest that is the bug.

Exporting from Acrobat as PostScript and re-distilling will produce a PDF that works in Catalina.

Exporting from Preview in another version of macOS will also produce a version that works in Catalina. (Exporting, not just Save As..)

Ghostscript produces a single blank page when trying to process the PDF.

The file was originally created using Acrobat 3, in 2001 on some Windows OS. While such systems should have been creating perfectly decent PDFs, something seems to have gone wrong here.