I believe it was Grok. I go back and forth between Chat and Grok to see if I can detect either of them changing, and by my estimation, Grok was faster this week than previously, and another odd thing occurred which hadn't happened so suddenly and dramatically before.
It gave me what I knew was a wrong answer, and I told it so. I do that out of curiosity, because in my experience sometimes they'll correct themselves, other times they'll deny that they were wrong. This time Grok denied it was wrong and said "I was just giving you the cold, hard facts". It was speaking normally, as it does when you first start a session. I was about to navigate away so, just as a final comment/joke I said "But I wanted the warm, soft facts".
Wow, this prompted an immediate change into what was a barrage of very nearly soft-core porn flirting with me, complete with red-lipped kissing emojis, hearts, etc. for two long paragraphs. When I typed in "want", "warm" and "soft", I was only posting opposite words of its words. I promise I was not even thinking erotically.

But I got lite erotica back, lol.
And of course it was encouraging me to continue to engage in more of the erotica, which was kinda special since my wife never does.