Mouse look is jittery and slow

Question

I'm using the mouse for looking around and it is working properly when looking up and down, but when looking left or right it moves really slow and it has jittery movement. I don't see why.

Here is my Movement class: 

    public class Movement : MonoBehaviour
    {
        [SerializeField] CharacterController controller;
        [SerializeField] float speed = 15f;
        Vector2 horizontalInput;
        [SerializeField] float jumpHeight = 3.5f;
        bool jump;
        [SerializeField] float gravity = -30f; //-9.81
        Vector3 verticalVelocity = Vector3.zero;
        [SerializeField] LayerMask groundMask;
        bool isGrounded; 
    
        private void Update()
        {
    
            isGrounded = Physics.CheckSphere(transform.position, 0.1f, groundMask);
            if (isGrounded)
            {
                verticalVelocity.y = 0; 
                }
            Vector3 horizontalVelocity = (transform.right * horizontalInput.x + transform.forward *
                horizontalInput.y ) * speed;
            controller.Move(horizontalVelocity * Time.deltaTime);
    
            // Jump: v = sqrt(-2 * jumpheight* gravity)
            if (jump)
            {
                if (isGrounded)
                {
                    verticalVelocity.y = Mathf.Sqrt(-2f * jumpHeight * gravity); 
                }
                jump = false;
            }
            verticalVelocity.y += gravity * Time.deltaTime;
            controller.Move(verticalVelocity * Time.deltaTime); 
    
        }
        public void ReceiveInput(Vector2 _horizontalInput)
        {
            horizontalInput = _horizontalInput;
        }
        public void OnJumpPressed() 
        {
            jump = true; 
        }
    }

MouseLook class:

    public class MouseLook : MonoBehaviour
    {
        [SerializeField] float sensitivityX = 8f;
        [SerializeField] float sensitivityY = 0.5f;
        float mouseX, mouseY;
    
        [SerializeField] Transform playerCamera;
        [SerializeField] float xClamp = 85f;
        float xRotataion = 0f; 
    
        private void Update()
        {
            transform.Rotate(Vector3.up, mouseX * Time.deltaTime);
            xRotataion -= mouseY; 
            xRotataion = Mathf.Clamp(xRotataion, -xClamp, xClamp);
            Vector3 targetRotation = transform.eulerAngles;
            targetRotation.x = xRotataion; 
            playerCamera.eulerAngles = targetRotation;
        }
        public void ReceiveInput(Vector2 mouseInput) 
        {
            mouseX = mouseInput.x * sensitivityX;
            mouseY = mouseInput.y * sensitivityY;
        }
    }

Because I'm using the new input system here is my InputManager class:

    public class InputManager : MonoBehaviour
    {
        [SerializeField] Movement movement;
        [SerializeField] MouseLook mouseLook; 
        PlayerControls controls; 
        PlayerControls.GroundMovementActions groundMovement;
        Vector2 horizontalInput; 
        Vector2 mouseInput;
    
      private void Awake() 
      {
            controls = new PlayerControls(); 
            groundMovement = controls.GroundMovement;
    
            // groundMovement.[action].performed += context => do something
            groundMovement.HorizontalMovement.performed += ctx => horizontalInput = ctx.ReadValue<Vector2>();
            groundMovement.Jump.performed += _ => movement.OnJumpPressed();
            groundMovement.MouseX.performed += ctx => mouseInput.x = ctx.ReadValue<float>();
            groundMovement.MouseY.performed += ctx => mouseInput.y = ctx.ReadValue<float>();
        }   
    
        private void Update()
        {
            movement.ReceiveInput(horizontalInput); 
            mouseLook.ReceiveInput(mouseInput);
        }
    
        private void OnEnable()
        {
            controls.Enable(); 
        }
    
        private void OnDestroy()
        {
            controls.Disable(); 
        }
    }

I tried setting sensitivityX to a larger number but the jitter effect is still there. How would I fix that and make it smooth?