DataStore2 OnUpdate

Is DataStore2’s OnUpdate cross-server? I am aware that normal Roblox DataStore’s OnUpdate is deprecated, and that we should use MessagingService instead for updating DataStores across servers, but DataStore2 also has an :OnUpdate function, so I was wondering if that method was cross-server.

Yes, it is cross-server (and it’s what developers used prior to MessagingService to send cross-server messages). However, keep in mind that, like you said, MessagingService is recommended and that OnUpdate has some unresolved issues, thus you shouldn’t be using it at all.