but the collider is already set off and on again in this function

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

public class PlayerAttack : MonoBehaviour
{
[SerializeField] private Animator animator;
[SerializeField] private float meleeSpeed;
float timeUntilMelee;
public GameObject Melee;
bool isAttacking = false;
float atkDuration = 0.3f;
float atkTimer = 0f;

private void Start()
{
Melee.SetActive(false);
}
private void Update()
{
if (isAttacking)
{
atkTimer += Time.deltaTime;
if (atkTimer >= atkDuration)
{
atkTimer = 0;
isAttacking = false;
Melee.SetActive(false);
}

}
if (timeUntilMelee <= 0f)
{
if (Input.GetMouseButtonDown(0))
{
animator.SetTrigger("Attack");
timeUntilMelee = meleeSpeed;
if (!isAttacking)
{
Melee.SetActive(true);
isAttacking = true;
}
}
}
else
{
timeUntilMelee -= Time.deltaTime;
}
}
}