The meaning of psychosis hasn't changed from before AI. It means loss of touch with reality. It's still somewhat subjective because people can interpret reality in different ways.

But to me what you are describing is pretty close to it. Because we know there was never any harmonic resonance and or "strange emergent state between two interlocutors".

I say this as somebody who uses the frontier models everyday for work. They are impressive and useful, but transformer intelligence is not at all like human intelligence, even if it superficially resembles human thinking. That should become more obvious the more you use them, not less.