I found a related question but it doesn't have what I needed.
- Client A sends input to move at T0.
- Server receives input at T1.
- All clients receive the change at T2.
With client-side prediction, client A would start moving at T0, client-side. All other clients receive the change at T2, so to them, client A only started moving at T2.
If I understand correctly, client B will always see client A's past position and not his current position? How do I sync both client B and client A?