I apologize for submitting a duplicate. I wrongly assumed that I would not be allowed to submit a link if it had not garnered attention within the last year or so (now I know 10 months is not "the last year or so") by an automated system. I did not realize that this was a responsibility of the moderator and I am sorry for any inconvenience I may have caused.
No worries and no need to apologize! The software catches some, users catch some, mods catch some, and the handful of dupes that end up getting through are basically harmless.
Macroexpanded list:
A List of Hacker News's Undocumented Features and Behaviors (2018-20) - https://news.ycombinator.com/item?id=26866482 - April 2021 (255 comments)
A List of Hacker News's Undocumented Features and Behaviors (2018) - https://news.ycombinator.com/item?id=23439437 - June 2020 (266 comments)
A List of Hacker News's Undocumented Features and Behaviors - https://news.ycombinator.com/item?id=20292361 - June 2019 (25 comments)
A List of Hacker News's Undocumented Features and Behaviors - https://news.ycombinator.com/item?id=19212822 - Feb 2019 (183 comments)