How to destroy only a clone in Unity 3d?

I have a tank:

 using UnityEngine;
 
 public class TankScript : MonoBehaviour
 {
     public static int health = 100;
     public GameObject tankItemPrefab;
 
     void Update()
     {
         if (health <= 0)
         {
             Instantiate(tankItemPrefab, transform.position, transform.rotation);
             Destroy(gameObject);
         }
     }
 }

When his health drops to zero, he must destroy himself and create a tankItem at the place of his death. Everything works, but for some reason all tanks are destroyed. How to fix it?