It appears that the ChatGPT subreddit may have stumbled upon something resembling the anomalous (or perhaps merely 'weird') tokens purely by accident a couple weeks ago in the following thread: https://www.reddit.com/r/ChatGPT/comments/10g6k7u/truly_bizarre_chatgpt_mistake_it_kept/
Perhaps so, but in the comments people report trying it in several different contexts, some of which don't appear to involve a list structure. Even more interestingly, somewhere in the comments someone claims it seems to have gotten 'patched' as of Jan 30. I wonder what that would entail.