When I opened my ChatGPT tab to ight there was a message:
Your GPT can now learn from your chats
Keep the conversation going
Your GPT will carry what it learns between chats, allowing it to provide more relevant responses.
Improves over time
As you chat your GPT will become more helpful, remembering details and preferences.
Manage what it remembers
Your GPT has been designed to follow your instructions in chats. You can reset your GPT's memory or turn this feature off in settings.
Notably, this comes after the release of
1) "Custom instructions" in the settings to manually modify your system prompts.
2) Retrieval as part of Assistants API (RAG)
3) The "GPT" builder allowing you to define how the system responds via chats (I assume this uses chats to define system prompts)
Feels like a natural extension of these to me. If someone extracted the new system prompt, I would expect to see a section on this similar to custom instructions.