Ugly math in preview of Wikipedia pdfs

When I "download as PDF" a Wikipedia article with math, such as
Septic_equation,
and open it in preview 8.0 on macos 10.10, the math formulas are ugly / munged:

instead of like in the browser (firefox) page

Before starting down the rocky road "what's wrong: fonts, preview, versionitis …"
let me ask

• does anyone else have the same problem
• are there print-ready .pdf or maybe .tex (not .html) for Wikipedia pages somewhere ?

Wikipedia:Rendering_math —

This page in a nutshell: There exist at least three different forms of math formulae on Wikipedia pages, with at least seven ways to present them. None is completely satisfactory.

However I have no idea which ones are used in which articles,
so which ones survive math — pdf — preview — print.
(Test cases for the 3 or 7 ways would be useful.)

Fonts might be a red herring, but here's pdfinfo, pdffonts anyway —

pdfinfo Septic_equation.pdf  # http://www.xpdfreader.com

Creator:        Chromium
Producer:       Skia/PDF m83
Tagged:         no
Form:           none
Pages:          3
Encrypted:      no
Page size:      594.96 x 841.92 pts (A4) (rotated 0 degrees)
File size:      673156 bytes
Optimized:      no
PDF version:    1.4

pdffonts Septic_equation.pdf  # all embedded ?
name                                           type              emb sub uni prob object ID
---------------------------------------------- ----------------- --- --- --- ---- ---------
LiberationSans                                 CID TrueType      yes no  yes           7  0
LiberationSerif-Italic                         CID TrueType      yes no  yes           8  0
LiberationSerif-Bold                           CID TrueType      yes no  yes           9  0
LiberationSerif                                CID TrueType      yes no  yes          10  0
LiberationSans-Bold                            CID TrueType      yes no  yes          11  0
LiberationSans-Italic                          CID TrueType      yes no  yes          85  0

When I export this in preview, the export.pdf is bigger ??

Creator:        Preview
Producer:       Mac OS X 10.10.5 Quartz PDFContext
Tagged:         no
Form:           none
Pages:          3
Encrypted:      no
Page size:      595.276 x 841.89 pts (A4) (rotated 0 degrees)
File size:      888908 bytes
Optimized:      no
PDF version:    1.3

name                                           type              emb sub uni prob object ID
---------------------------------------------- ----------------- --- --- --- ---- ---------
ZWJFYX+LiberationSans-Bold                     CID TrueType      yes yes yes          14  0
VOJIYC+LiberationSans                          CID TrueType      yes yes yes          10  0
VBAANE+LiberationSerif-Bold                    CID TrueType      yes yes yes          12  0
ESNUES+LiberationSerif-Italic                  CID TrueType      yes yes yes          11  0
CQEMAV+LiberationSerif                         CID TrueType      yes yes yes          13  0
POYZKZ+LiberationSans-Italic                   CID TrueType      yes yes yes          31  0