It’s most likely related to ChatGPT’s memory feature, which gets gradually rolled out, updated, and tested on different users. This memory system is separate from your chat history, so deleting conversations does not delete what the memory module has stored.
This means a few things can happen:
ChatGPT may recall details even if you deleted the chat where they were mentioned.
It can automatically re-learn things like your name or preferences during normal use.
Updates to the UI or internal systems can make the model appear to “remember more” all of a sudden, even if it’s just the memory feature being reactivated or improved.
This isn’t a sign of increased “awareness” or anything like that just how the product’s long-term preference system works.
If you don’t want ChatGPT to retain anything across sessions, you can disable or clear memory here:
Settings → Personalization → Memory → Turn off / Clear Memory
So what you’re seeing is almost certainly a product update or memory feature behavior, not a bug in the sense of the model retrieving deleted history.