Hey, I'm working on an input system, but somehow it doesn't work anymore

I worked on and completed this Tutorial the day before, today I wanted to implement it in my real game and suddenly it didn't work anymore, somehow the scripts no longer want to communicate with each other even though I only added a few variables. There is a: public static GameManager GM;

here are the Scripts: Number 1 = GameManager.cs

 public class GameManager : MonoBehaviour
 {
 
     public static GameManager GM;
 
     public KeyCode drift { get; set; }
     public KeyCode forward { get; set; }
     public KeyCode backward { get; set; }
     public KeyCode left { get; set; }
     public KeyCode right { get; set; }
     public KeyCode restart { get; set; }
     public KeyCode menu { get; set; }
     public KeyCode item { get; set; }
 
     void Awake()
     {
         if (GM == null)
         {
             DontDestroyOnLoad(gameObject);
             GM = this;
         }
         else if (GM != this)
         {
             Destroy(gameObject);
         }
         
         drift = (KeyCode)System.Enum.Parse(typeof(KeyCode), PlayerPrefs.GetString("driftKey", "Space"));
         forward = (KeyCode)System.Enum.Parse(typeof(KeyCode), PlayerPrefs.GetString("forwardKey", "W"));
         backward = (KeyCode)System.Enum.Parse(typeof(KeyCode), PlayerPrefs.GetString("backwardKey", "S"));
         left = (KeyCode)System.Enum.Parse(typeof(KeyCode), PlayerPrefs.GetString("leftKey", "A"));
         right = (KeyCode)System.Enum.Parse(typeof(KeyCode), PlayerPrefs.GetString("rightKey", "D"));
         restart = (KeyCode)System.Enum.Parse(typeof(KeyCode), PlayerPrefs.GetString("restartKey", "R"));
         menu = (KeyCode)System.Enum.Parse(typeof(KeyCode), PlayerPrefs.GetString("menuKey", "M"));
         item = (KeyCode)System.Enum.Parse(typeof(KeyCode), PlayerPrefs.GetString("itemKey", "LeftControl"));
 
     }
 }

and number 2 is the UI Menu Script also in C#

 public class Controlsscript : MonoBehaviour
 {
     Transform menuPanel;
     Event keyEvent;
     Text buttonText;
     KeyCode newKey;
 
     bool waitingForKey;
 
     // Start is called before the first frame update
     void Start()
     {
         menuPanel = transform.Find("Panel");
         menuPanel.gameObject.SetActive(false);
         waitingForKey = false;
 
         for (int i = 0; i < 8; i++)
         {
             
             if (menuPanel.GetChild(i).name == "ForwardKey")
                 menuPanel.GetChild(i).GetComponentInChildren<Text>().text = GameManager.GM.forward.ToString();
             if (menuPanel.GetChild(i).name == "BackwardKey")
                 menuPanel.GetChild(i).GetComponentInChildren<Text>().text = GameManager.GM.backward.ToString();
             if (menuPanel.GetChild(i).name == "LeftKey")
                 menuPanel.GetChild(i).GetComponentInChildren<Text>().text = GameManager.GM.left.ToString();
             if (menuPanel.GetChild(i).name == "RightKey")
                 menuPanel.GetChild(i).GetComponentInChildren<Text>().text = GameManager.GM.right.ToString();
             if (menuPanel.GetChild(i).name == "DriftKey")
                 menuPanel.GetChild(i).GetComponentInChildren<Text>().text = GameManager.GM.drift.ToString();
             if (menuPanel.GetChild(i).name == "RestartKey")
                 menuPanel.GetChild(i).GetComponentInChildren<Text>().text = GameManager.GM.restart.ToString();
             if (menuPanel.GetChild(i).name == "MenuKey")
                 menuPanel.GetChild(i).GetComponentInChildren<Text>().text = GameManager.GM.restart.ToString();
             if (menuPanel.GetChild(i).name == "ItemKey")
                 menuPanel.GetChild(i).GetComponentInChildren<Text>().text = GameManager.GM.restart.ToString();
 
 
         }
     }
 
     // Update is called once per frame
     void Update()
     {
         
         if (Input.GetKeyDown(KeyCode.Escape) && !menuPanel.gameObject.activeSelf)
             menuPanel.gameObject.SetActive(true);
         else if (Input.GetKeyDown(KeyCode.Escape) && menuPanel.gameObject.activeSelf)
             menuPanel.gameObject.SetActive(false);
         
     }
 
     void OnGUI()
     {
         keyEvent = Event.current;
 
         if (keyEvent.isKey && waitingForKey)
         {
             newKey = keyEvent.keyCode;
             waitingForKey = false;
         }
     }
 
     public void StartAssignment(string keyName)
     {
         if (!waitingForKey)
         {
             StartCoroutine(AssignKey(keyName));
         }
     }
 
     public void SendText(Text text)
     {
         buttonText = text;
     }
 
     IEnumerator WaitForKey()
     {
         while (!keyEvent.isKey)
         {
             yield return null;
         }
     }
 
     public IEnumerator AssignKey(string keyName)
     {
         waitingForKey = true;
 
         yield return WaitForKey();
 
         switch (keyName)
         {
             case "forward":
                 GameManager.GM.forward = newKey;
                 Debug.Log("Neuer Key");
                 buttonText.text = GameManager.GM.forward.ToString();
                 PlayerPrefs.SetString("forwardKey", GameManager.GM.forward.ToString());
                 break;
             case "backward":
                 GameManager.GM.backward = newKey;
                 buttonText.text = GameManager.GM.backward.ToString();
                 PlayerPrefs.SetString("backwardKey", GameManager.GM.backward.ToString());
                 break;
             case "left":
                 GameManager.GM.left = newKey;
                 buttonText.text = GameManager.GM.left.ToString();
                 PlayerPrefs.SetString("leftKey", GameManager.GM.left.ToString());
                 break;
             case "right":
                 GameManager.GM.right = newKey;
                 buttonText.text = GameManager.GM.right.ToString();
                 PlayerPrefs.SetString("rightKey", GameManager.GM.right.ToString());
                 break;
             case "drift":
                 GameManager.GM.drift = newKey;
                 buttonText.text = GameManager.GM.drift.ToString();
                 PlayerPrefs.SetString("driftKey", GameManager.GM.drift.ToString());
                 break;
             case "restart":
                 GameManager.GM.restart = newKey;
                 buttonText.text = GameManager.GM.restart.ToString();
                 PlayerPrefs.SetString("restartKey", GameManager.GM.restart.ToString());
                 break;
             case "menu":
                 GameManager.GM.menu = newKey;
                 buttonText.text = GameManager.GM.menu.ToString();
                 PlayerPrefs.SetString("menuKey", GameManager.GM.menu.ToString());
                 break;
             case "item":
                 GameManager.GM.item = newKey;
                 buttonText.text = GameManager.GM.item.ToString();
                 PlayerPrefs.SetString("itemKey", GameManager.GM.item.ToString());
                 break;
         }
         yield return null;
     }
 
     public void resetAllKeybinds()
     {
         PlayerPrefs.DeleteKey("forwardKey");
         PlayerPrefs.DeleteKey("backwardKey");
         PlayerPrefs.DeleteKey("leftKey");
         PlayerPrefs.DeleteKey("rightKey");
         PlayerPrefs.DeleteKey("driftKey");
         PlayerPrefs.DeleteKey("restartKey");
         PlayerPrefs.DeleteKey("menuKey");
         PlayerPrefs.DeleteKey("itemKey");
     }
 }
 

and somehow they communicated yesterday and today they don't want to (I just changed on or two Variable names and added a bit not changed anything important)