Camera movement by OY coordinate

Hello i have a problem with following camera. It cant follow player by OY coordinate. my code:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class camera : MonoBehaviour
 {
     public Transform target;
     public Vector3 positionOffset;
     public float smooth = 3.0f;
 
 void Start()
 {
     positionOffset = gameObject.transform.position - target.position;
 }
 void LateUpdate()
 {
     transform.position = Vector3.Lerp(transform.position, new Vector3(target.position.x + 
     positionOffset.x, positionOffset.y, target.position.z + positionOffset.z), Time.deltaTime 
    * smooth);
     }
 }

Also link of video where i recorded of my problem:https://youtu.be/0RCEmrw3Xho