Stack Exchange suffers from some zero-width space characters being inserted in the post data quite infrequently when the text "values " (with a trailing space) is being used.
For people not too familiar with invisible unicode characters, you may copy-paste the content from the below examples to an online editor like the green textarea from https://r12a.github.io/app-conversion/ and tap Convert, then you'll discover the hidden single or double spaces
U+200B that were inserted.
Now, this bug doesn't happen all the time... from my analysis, it happens maybe 1 time out of 500 usages of text "values ". But with the amount of posts on the Stack Exchange network, I was easily able to find with SEDE thousands of occurrences of this issue across Stack Exchange.
Demonstration that the bug, when it kicks in, affects both the title and the body of the post:
Demonstration that it also affects Mathematics (and not just Stack Overflow):
Demonstration that to trigger the bug, the pattern doesn't require a space before "values " (but requires one after):
Demonstration that it doesn't affect all posts, by comparing some recent posts created on the same day (Oct 26, 2018):
Potentially oldest Stack Overflow post affected:
- How to access to a NSArray, after extract values from a json file from 2011-06-08 09:42:07Z
Which could mean that the bug wasn't there in 2008/2009/2010.