Kill counter doesn't stop counting

After i kill the enemy instead of adding one point it adds infinite number of points even after i pause the game it doesn't stop.

Here is my game manager script; using System.Collections; using System.Collections.Generic; using UnityEngine; using TMPro;

public class UIManager : MonoBehaviour { public static UIManager instance; [SerializeField] TextMeshProUGUI killCounter_TMP; [HideInInspector] public int killCount ;

 private void Awake()
 {
     if (instance == null)
     {
         instance = this;
     }
     else
     {
         Destroy(gameObject);
     }
 }
 public void UpdateKillCounterUI()
 {
     killCounter_TMP.text = killCount.ToString();
 }

}

and here is my enemy health script; using System.Collections; using System.Collections.Generic; using UnityEngine; using UnityEngine.UI;

public class EnemyScript : MonoBehaviour { public int EnemyHealth = 10; public GameObject TheZombie; void DeductPoints(int DamageAmount) { EnemyHealth -= DamageAmount;

 }
 void Update()
 {
    
     if (EnemyHealth <= 0)

     { 
         this.GetComponent<ZombieFollow>().enabled = false;
         this.TheZombie.GetComponent<Animation>().Play("Dying");
         UIManager.instance.killCount++;
         UIManager.instance.UpdateKillCounterUI();
         EndZombie();
     }

 }

 IEnumerator EndZombie()
 {
     yield return new WaitForSeconds(3);
     Destroy(gameObject);

}

}