Who or what is injecting "data-contrast" spans into my website (at night) and how to stop it?

Question

It has been brought to my attention that a website I'm helping out with sometimes has problems with span elements being injected. Those spans will break the whitespaces and make the text hard to read. Those spans look something like this:

<span data-contrast="auto">words</span>
<span data-contrast="auto">,</span>
<span data-contrast="auto">b</span>
<span data-contrast="auto">ut</span>
<span data-contrast="auto">sometimes also only single chars</span>

The website is run with/by WordPress, but that does not seem to be the cause because the affected posts look fine and show no sign of this markup in the post editor or database.

Also, those spans only seem to occur at nighttime. I tried to nail that down, but as so often, I couldn't really verify it yet, as it did not occur again to me, not even at night. Right now everything is fine and none of these spans are present.

I'm guessing it has got something to do with night-mode in browsers (although behaviour was the same in Edge and Firefox) or the night-mode in Windows but then on the other hand I haven't noticed this on any other page yet.

So, this is somewhat strange and hard to nail down, but you'll find copied texts that contain the same markup, when you use a search engine and search for "data-contrast span". So, at least I'm not the only one with this problem.

Any ideas how to nail this down and find out what causes it?

Answer 1

Since it's not clear what software they are copying from, I've personally experienced this when copying from a Word Doc that's been opened in Microsoft Teams or in SharePoint, and then pasting directly into a website's editor (our site uses the TinyMCE text editor, a commonly utilized free text editor).

My recommendation: copy directly from the desktop version of Word, then paste into the editor and that prevents the "data-contrast" spans.

I assume there must be some hidden spans in non-desktop versions of Word Docs that they add to ensure the document displays the same way as the desktop version. The text editor doesn't know what to do with it, so it strips out everything, but the "data-contrast" portion.

Hope this helps someone out there as the original post was as asked some time ago.