AI engineers are not a unitary group with opinions all aligned. Some of them really like money too. Or just want to build something that changes the world.

I don’t know of a specific “when” where a bunch of engineers left OpenAI all at once. I’ve just seen a lot of articles over the past year with some variation of “<company> is a startup founded by former OpenAI engineers.” There might have been a surge when Altman was briefly ousted, but that was brief enough that I wouldn’t expect a visible spike on the graph.