[pax]

Эх....

Ray ray = cam.ScreenPointToRay(Input.mousePosition); //
        RaycastHit hit;
        
        if (Physics.Raycast(ray, out hit)) {
            var lookDirection = hit.point - transform.position;
            lookDirection.y = 0;
            var targetRotation = Quaternion.LookRotation(lookDirection);
            transform.rotation = Quaternion.Slerp(transform.rotation, targetRotation , turnSpeed * Time.deltaTime);
        }