Last night I posted a comment on this question, which was open at the time but has since been closed as a duplicate. This morning, I see a notification in my inbox that someone else posted a comment using @JulianRosen (I see part of the comment in my inbox). When I visit the question, my comment and the reply are gone. Can someone tell me what became of the missing comments?
All comments linking out to duplicate candidates are automatically deleted when the question is closed. The system cleans them up for being obsolete.
Sometimes this can result in weird and unwanted behavior, but it's pretty uncommon.