White lines appear on some images when viewing pdf documents with Firefox pdf viewer

I do see these (on macOS 15 hiDPI/retina) only on page 9 "Director of Environmental Health", and page 3 bottom right image — attaching the previews here. These seem to appear and disappear based on zoom level — if you're aware of more occurrences please do note them as well — in case these render differently for different consumers.

Those are the two instances on that document. I have also seen a draft version of the next Newsletter and that has similar problems. I agree that the lines move about with zoom but don't disappear. Opening the same document with Opera there are no problems at any level of zoom. Using Firefox on my phone also shows the same problem!

Yes, I compared to reference system PDF preview and these do not render elsewhere. It doesn't seem to exhibit on smaller (lower resolution, smaller file size) images — correlating that to chunked larger images coming from msword this sounds like an existing issue: https://github.com/mozilla/pdf.js/issues/3351#issuecomment-77674812

One of the later reports looks exactly like this: https://github.com/mozilla/pdf.js/issues/17745 so this falls into the class of issues being tracked already, thanks!

OK I don't see I can mark it as solved but do I need to do anything else to help those working on the problem?

It seems they have a good amount of samples attached (there was a previous support.mozilla.org/questions/1449535 showing the same) so this gets enough reports on that canonical ticket itself.

You can just pick any of the posts here as the solution and it will resolve the question here for now.

Any updates will happen via the linked ticket.