That's HN's "second chance" feature. The relative timestamps are faked to look new so the discussion doesn't look stale. The real time stamps are still displayed on hover / in the alt text. I'm not sure why this was second chanced four days later considering that it spent a fair amount of time on the front page. Maybe a misclick.

e: misremembered, it apparently wasn't on the front page: https://hnrankings.info/39786663/