Hi, with your code above, the client can set any movement speed on the server that he wants, so if the client would cheat, he could set any movement speed that he wants.
Generally speaking for game relevant things I find it a good way to see the client only as keyboard plus monitor but no logic (player input that is directly relayed to the server and then the client watches through the monitor what the server does, but the client doesn’t execute any game relevant code, only cosmetic things. For example if the player would shoot a weapon, then the client could directly spawn the sound and particle systems, maybe even a bullet so that the player has direct response but all game relevant things like the damage should happen on the server).