1. ChatGPT reliably produces the same output across several different instances, and other people have independently found identical versions of this text with different prompts.[1][2] This typically wouldn't happen with a hallucination, which may change with each time the model is prompted.
2. The instructions accurately describe the capabilities and restrictions of ChatGPT's function calls. When making custom GPTs, the browser tool and DALL-E image generation tool are options, and the "system prompt" given by the custom GPTs reflect whichever tools you've selected.
3. ChatGPT has reliably changed with the changes noticed in the "system prompt". I document a recent change made to the prompt on my post from yesterday.[3] On the older instances of ChatGPT I have, the model will suggest it has no idea what the "guardian_tool" is or make any attempt at stopping a discussion of U.S. elections, while newly made instances of ChatGPT will discuss the "guardian_tool". The "system prompt" repeated then must give at least some sense of what updates are being made under the hood.
I certainly think we should still take the idea that this is the "system prompt" with a grain of salt. There is a good discussion about this here: https://news.ycombinator.com/item?id=37879077
[1] https://www.reddit.com/r/ChatGPT/comments/18494zo/what_are_t...
[2] https://medium.com/@dan_43009/what-we-can-learn-from-openai-...
[3] https://dmicz.github.io/machine-learning/chatgpt-election-up...