Affected versions

• Firefox 95.0b12
• Firefox 96.0a1

Affected platforms

• Ubuntu 20.04
• macOS 11.6.1
• Windows 10

Steps to reproduce

1. Launch Firefox
2. Access this mozilla page
3. Launch Print preview and select Save to PDF
4. Print the file to PDF

Expected result

• All the content is printed in the PDF

Actual result

• There is missing content in the printed PDF

Regression range

• Will see for a regression

Additional notes

• The issue can be seen in the attachment
• The issue may be reproducing on other websites based on content like this one
• Print headers and footers and Print Backgrounds are also checked

(In reply to Catalin Sasca, QA [:csasca] from comment #0)

Actual result

• There is missing content in the printed PDF

Specifically: on my system, pages 10 to 24 are entirely blank (aside from headers/footers), and earlier pages are noticeably missing content at the top (progressively more content on each page) when compared to print-preview. e.g. on my system, Print Preview shows "Permitted content" at the top of page 3, but that's clipped (due to the page-content being shifted upwards) in the PDF printout.

This looks like the same issue as bug 1740304.

I confirmed that this bug doesn't reproduce in a build with the patch that I've just posted on bug 1740304.