how to stop Instantiate after 3 minuts,trying to stop Instantiate after 3 minuts

@strespro you can for sure use coroutine but i personally never use it so what you can do is -:

 public class EnemySpawner : MonoBehaviour
      {
          public float SpawnRate;
          public float SpawnStart;
          public GameObject EnemyPrefab;
          public float MaxSpeed;
          public float MinSpeed;
          Vector2 Min;
          Vector2 Max;
          public GameObject StopSpawning;
          public float stop_time = 180f; // a new float declaration
      
          void Start()
          {
              Min = Camera.main.ViewportToWorldPoint(new Vector3(0, 0));
              Max = Camera.main.ViewportToWorldPoint(new Vector3(1, 1));
              InvokeRepeating("SpawnerEnemy", SpawnStart, SpawnRate);
             
          }
      
          void SpawnerEnemy(float v )
          {
              float ExtendsX = EnemyPrefab.GetComponent<Renderer>().bounds.extents.x;
              float ExtendsY = EnemyPrefab.GetComponent<Renderer>().bounds.extents.y;
              float RandomX = Random.Range(Min.x + ExtendsX, Max.x - ExtendsX);
              Vector2 RandomPosition = new Vector2(RandomX, Max.y+ExtendsY);
              GameObject Enemy = Instantiate(EnemyPrefab, RandomPosition, Quaternion.identity);
              Enemy.GetComponent<EnemyController>().Speed = Random.Range(MinSpeed, MaxSpeed);
          }
          void Update()
          {
             if (stop_time <= 0){
                 CancelInvoke("SpawnerEnemy");
               }
             else{
                stop_time -= Time.deltaTime;
               }
          }
        
      }

i am just subtracting time with Time.deltaTime which is the time taken to render each frame. hope this helps

You should just use a co-routine and you will be good to go. In simple words, co-routines allow you to "control" the timing after which a piece of code will get executed. You can, and should, read up more about them : https://docs.unity3d.com/Manual/Coroutines.html

So, your code should look like this :

 void SpawnerEnemy(float v)
     {
         float ExtendsX = EnemyPrefab.GetComponent<Renderer>().bounds.extents.x;
         float ExtendsY = EnemyPrefab.GetComponent<Renderer>().bounds.extents.y;
         float RandomX = Random.Range(Min.x + ExtendsX, Max.x - ExtendsX);
         Vector2 RandomPosition = new Vector2(RandomX, Max.y + ExtendsY);
         GameObject Enemy = Instantiate(EnemyPrefab, RandomPosition, Quaternion.identity);
         Enemy.GetComponent<EnemyController>().Speed = Random.Range(MinSpeed, MaxSpeed);
         StartCoroutine(StopSpawning());
     }
 
     private IEnumerator StopSpawning()
     {
         yield return new WaitForSeconds(180f);
         CancelInvoke("SpawnerEnemy");
     }

Also, I noticed you were checking whether the instantiated enemy prefab was inactive before cancelling the invoked repeating function, which is not needed if all you needed was to stop instantiating after 3 mins. Let me know further if you wanted to achieve something else.