This is a Chromium specific bug and is reported since the beginning of the year.
https://support.google.com/chrome/thread/66790726?hl=en
https://bugs.chromium.org/p/chromium/issues/detail?id=1123389&q=fast%20web%20view&can=2
The problem is due the Web Optimization options on the software exporting the PDF.
If you want to render it on Chrome, disable this option. This thread also covers the problem
https://moodle.org/mod/forum/discuss.php?d=408359#p1649501
I did't have the PDF source, so I followed this process:
Split the PDF on many PNGs with https://pdf2png.com/
Merge the PNGs with https://pdf2png.com/
If there were too many images. I used Imagemagic to merge all PNGs on a folder with this command:
convert *.png merged.pdf
