Why when clamping a cinemachine free look camera with a script the camera is stuttering ?

The script is attached to an empty GameObject.
The clamping part is in the Update.

In the Inspector I set the Clamp Min value to 0 and the Clamp Max value to 3.
The Pitch value is 0.
The Speed is set to 0.3.

In the camera settings in the Inspector I changed the Axis Control > Y Axis > Speed value to 0.

but when running the game and moving the camera around with the mouse the camera is kind of stuttering and not moving smooth. and it happens once I’m using this script.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using Cinemachine;

public class CamerasManager : MonoBehaviour
{
    public CinemachineFreeLook[] freeLookCameras;
    public float timeBeforeSwitching;
    public float clampMin;
    public float clampMax;
    public float pitch;
    public float speed;

    // Start is called before the first frame update
    void Start()
    {
        StartCoroutine(SwitchCameras(timeBeforeSwitching));
    }

    // Update is called once per frame
    void Update()
    {
        pitch += speed * Input.GetAxis("Mouse Y");
        pitch = Mathf.Clamp(pitch, clampMin, clampMax);
        freeLookCameras[1].GetRig(1).GetCinemachineComponent<CinemachineComposer>().m_TrackedObjectOffset.y = pitch;
    }

    IEnumerator SwitchCameras(float TimeBeforeSwitching)
    {
        yield return new WaitForSeconds(TimeBeforeSwitching);

        freeLookCameras[0].enabled = false;
        freeLookCameras[1].enabled = true;
    }
}

I don’t think you can interoperate with cinemachine from outside like that. You’d just be fighting it. Aren’t there already some clamping facilities in cinemachine? You should use those.