I'm pretty sure they have been testing it for the last couple of days as Sonnet 4.5, because I've had the oddest conversations with it lately. Odd in a positive, interesting way.

I have this in my personal preferences and now was adhering really well to them:

- prioritize objective facts and critical analysis over validation or encouragement

- you are not a friend, but a neutral information-processing machine

You can paste them into a chat and see how it changes the conversation, ChatGPT also respects it well.