Everytime when i start at level 3 or higher after completing it it goes back to level 2 how do i fix this?

I made a game from a tutorial on youtube and i have an level selection scene after you press play but know when i go to level 3 or higher from that level selection scene and i complete that level i am goin back to level 2 but when i start at level 1 or 2 i just go to the right scenes.

All my levels are called
Level1
Level2
Level3
Level4
etc.

so this code should work.

public class LevelController : MonoBehaviour
{
    private static int _nextLevelIndex = 1;
    private Enemy[] _enemies;

    private void OnEnable()
    {
        _enemies = FindObjectsOfType<Enemy>();
    }

    void Update()
    {
       foreach(Enemy enemy in _enemies)
        {
            if (enemy != null)
                return;
        }

        Debug.Log("You killed all enemies");

        _nextLevelIndex++;
        string nextLevelName = "Level" + _nextLevelIndex;
        SceneManager.LoadScene(nextLevelName);
    }
}

Here is the code for my level selection scene i dont think the problem is on this code

public class lvlControl : MonoBehaviour
{
   public void selectScene()
    {
        switch (this.gameObject.name)
        {
            case "Level1":
                SceneManager.LoadScene("Level1");
                break;

            case "Level2":
                SceneManager.LoadScene("Level2");
                break;

            case "Level3":
                SceneManager.LoadScene("Level3");
                break;

            case "Level4":
                SceneManager.LoadScene("Level4");
                break;


            case "Level5":
                SceneManager.LoadScene("Level5");
                break;


            case "Level6":
                SceneManager.LoadScene("Level6");
                break;


            case "Level7":
                SceneManager.LoadScene("Level7");
                break;


            case "Level8":
                SceneManager.LoadScene("Level8");
                break;
        }
    }
       
    
}

it all worked fine until i went from 4 to 8 levels and know it doesnt work anymore.

I hope someone knows how to fix this and i would really appreciate if you reply to this.

This should solve your problem.
Unity Answers Page

I also have a suggestion that is completely unrelated to your problem. Instead of using the switch statement in your second script, you could just write:

public void selectScene()
{
SceneManager.LoadScene(this.gameObject.name);
}