How to Instantiate single Prefabs from an array?

I'm trying to make a android game that is recording score with time, and the player needs to jump over obstacles as the speed get's faster in game.

But my spawn seems to instantiate all of the array and even more prefabs and then stop indefinitely.

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class ObstacleSpawner : MonoBehaviour
 {
     //For the start of the game a swipe must be done
     private Vector2 swipeStartPos;
     private Vector2 swipeEndPos;
 
 
 
     //array for obstacleprefabs trees
     public GameObject[] trees;
     int puud = 0;
     int maxPuud = 3;
     //second array for enemy prefabs
     public GameObject[] Enemies;
     int vastased = 0;
     int maxVastased = 1;
     public bool mängAlgas = false;
 
     public bool round2 = false;
 
     public GameObject Player;
 
     public int maximumObj;
 
     // Start is called before the first frame update
     void Start()
 
     {
 
        
 
         if (mängAlgas == true)
         {
             
             StartCoroutine(WaitForSecondsAndThenSpawn());
 
 
         }
 
     }
 
   
     void Update()
     {
         
 #if UNITY_EDITOR
         SwipeEnded();
        DetectMousePress();
 #else
         
         DetectTouchPress();
 #endif
 
     }
 
     private void SpawnTrees()
     {
         if (puud <= maxPuud)
         {
             print("I'm Spawning a tree.");
             
             float randomXValue = Random.Range(927f, 1500f);                       
             
             Vector2 spawnPos = new Vector2(randomXValue, 50f);
              
             Instantiate(PickRandomTree(), spawnPos, Quaternion.identity);            
             puud++;
         }
 
     }
     //private void SpawnEnemies()
     //{
     //    if (round2 == true)
     //    {
     //        if (vastased <= maxVastased)
     //        { 
     //        print("yo ma spawnin vastase");
     //            //sündimis vahe x teljel
     //        float randomXValue = Random.Range(927f, 1500f);        
     //            //Sündimis asukoht
     //        Vector2 spawnPos = new Vector2(randomXValue, 6.5f);                
     //            //sünnitamine
     //        Instantiate(PickRandomEnemy(), spawnPos, Quaternion.identity);
     //            vastased++;
     //        }
     //    }
 
     //}
 
     private GameObject PickRandomTree()
     {
         int randomNumber = Random.Range(0, trees.Length);
 
         GameObject treeThatWeChose = trees[randomNumber];
         return treeThatWeChose;
     }
     
     
     //SUVALISE VASTASE VALIMISEKS
     //private GameObject PickRandomEnemy()
     //{
     //    int randomNumber = Random.Range(0, Enemises.Length);
 
     //    GameObject EnemiesThatWeChose = Enemies[randomNumber];
     //    return EnemiesThatWeChose;
     //}
     IEnumerator WaitForSecondsAndThenSpawn()
         {
             yield return new WaitForSeconds(1.5f);
             SpawnTrees();       
             StartCoroutine(WaitForSecondsAndThenSpawn());
         
         }
     
     public void DetectTouchPress()
     {
         foreach (Touch touch in Input.touches)
         {
             if (touch.phase == TouchPhase.Began)
             {
                 //start of the touch
                 print("Touch began at" + touch.position);
                 swipeStartPos = touch.position;
             }
             if (touch.phase == TouchPhase.Ended)
             {
                 print("touch ended at" + touch.position);
                 swipeEndPos = touch.position;          
                 
             }
         }
     }
 
 
     //Mouse down - Mouse Up record
     public void DetectMousePress()
     {
         //print("Detection Button Input");
         if (Input.GetMouseButton(0))
         {
             //Start of the press
             //print("Mouse button was pressed at " + Input.mousePosition);
             swipeStartPos = Input.mousePosition;
         }
         if (Input.GetMouseButtonUp(0))
         {
             //End of the press
             //print("Mouse button was released" + Input.mousePosition);
             swipeEndPos = Input.mousePosition;
 
         }
      
     }
     public void SwipeEnded()
     {
         Vector2 swipeVector = swipeEndPos - swipeStartPos;
 
         if (Mathf.Abs(swipeVector.x) > Mathf.Abs(swipeVector.y))
         {
             print("swipe was horizontal");
             if (swipeVector.x < 0f)
             {
                 print("mäng algas");
                 mängAlgas = true;
                 Start();
             }
             
             
         }
    
     }
     
  
 
 }