You have no clue what you’re talking about. The desync isn’t some coincidence shared across platforms, it’s heavily tied to how Playstation servers handle their handshake and session-sync process. Those delays in establishing and validating the connection introduce the very desync issues people are complaining about.
So yes, crossplay can make things worse when one side’s network layer is slower, also I've tried crossplay off it and the game feels better.
Pretending it’s all just “netcode in general” is missing half the picture.
