Unity 2D Parallax Effect script with Cinemachine

ParallaxEffect.cs

using UnityEngine;
using Cinemachine;

public class ParallaxEffect : MonoBehaviour
{
    public Camera cam;
    public Transform subject;

    Vector2 startPosition;
    float startZ;

    Vector2 travel => (Vector2)cam.transform.position - startPosition;
    float distanceFromSubject => transform.position.z - subject.position.z;
    float clippingPlane => (cam.transform.position.z + (distanceFromSubject > 0 ? cam.farClipPlane : cam.nearClipPlane));
    float parallaxFactor => Mathf.Abs(distanceFromSubject) / clippingPlane;

    public void Start()
    {
        startPosition = transform.position;
        startZ = transform.position.z;
        // Subscribe to the CameraUpdatedEvent
        CinemachineCore.CameraUpdatedEvent.AddListener(OnCameraUpdated);
    }

    private void OnDestroy()
    {
        CinemachineCore.CameraUpdatedEvent.RemoveListener(OnCameraUpdated);
    }

    // This will be called after the camera is positioned
    void OnCameraUpdated(CinemachineBrain brain)
    {
        // Update the parallax effect based on the camera position (only affecting the X position)
        float newPosX = startPosition.x + travel.x * parallaxFactor;

        // Keep the original Y position, so it doesn't move vertically
        transform.position = new Vector3(newPosX, transform.position.y, startZ);
    }
}