For characters, controller’s “Control Rotation” is replicated from client to server by CharMoveComp, UCharacterMovementComponent::ServerMove_PerformMovement and ServerMove_Implementation
Unfortunately, that means that on pawns you’ll have to sync it yourself. Remember that because of high frequency ticks, in movement server function is unreliable, I’d recommend keeping it like this for your own Pawn server function where you set controller rotation according to client data.
I specified the code for a pawn, but you can also move it to an actor component with slight changes if you want.