The concept of "rollback netcode" is something that generally only applies to fighting games, shooters with dedicated servers use lag compensation instead which just means that, every time you shoot someone, the hit detection is done on the server but the server rolls back the player's position depending on your ping to make sure their position roughly matches what you saw when you shot. CSGO2 is just improving this so the rolled back player positions can be interpolated between frames instead of only being able to roll back to wherever a player was on an exact tick, which is what it currently does.