When I first signed up on a Stack Exchange site and got a profile image, it was this one (see my current user card):
Later, I got Area 51 and SEDE profiles, and my user image there was a different identicon. Because reasons I already know. I would have a picture of it, but that's the problem....
I noticed it with his avatar, too. In fact, in his chat profile I still see different gravatar than on the main. (Recently he briefly appeared in chat.)
But I think I have seen it for some other users, too. (To be more precise, at least for one other user.)
Nevertheless, the linked posts seem to document a few other cases.
@DanielFischer Did you change your avatar, or is chat rendering a different avatar than the one I've come to identify with you?
That would not surprise me, given the recent discussion here.
I also see Daniel F's and Brian M Scott's icon/avatar now also changed on main, not just chat???? Daniel: green, not brown, Brian's maroon, not green???