Surely the way streamers talk to "chat"? I've never heard anyone call ChatGPT "chat".

No, there are people who will say "ask Chat to explain it to you" in reference to ChatGPT.

All the people younger than 28yo in France, for sure.

That could be because to say ChatGPT in French sounds like "Chat I farted" (Chat j'ai pété)

isn't chat a cat in france