We’ve talked about seasons 1-3 of You and why this show has such a chokehold on people. But from the very beginning of season 4 it was very clear that we were getting into something very different. There has been a clear shift in season 4 and though that was true of every season before it, of there being slight tonal changes. Season 4 feels incredibly different in both story and tone.
https://vocal.media/geeks/you-season-4-pqql0b3c

At the end of the first part of the fourth season of You my current theory is that the stalker is none of these rich kids, I still like the idea of Marianne or Leo. The problem is the actual murder part…But we will see what part 2 has in store as far as answers go.