I found this on https://phabricator.wikimedia.org/T35704 and https://phabricator.wikimedia.org/T78050 - I assume it can be reproduced like this:
* Comment on a task
* Refresh the page to see "Older changes are hidden. Show older changes."
* Check that you can View Raw/Quote all shown comments.
* Show older changes.
* Can't View Raw/Quote on the newly-visible comments.