Given a setup where your client is predicting (tick 100) the actions that they think they will be doing once the server (currently tick 75) receives their input. When the client receives the world state from the server once it reaches and sends the results for tick 100, the client goes back in time to make sure it didn't mispredict. If it does, it has to do a full rollback to that tick (100) and repredict all the inputs up to the current client prediction tick (125 in this contrived example).
Let's assume the client has perfectly predicted …