How do I save a variable when the scene reloads?

I'm creating an endless jumper game where the player needs to jump on platforms to go up, but the scene is reloaded when they fall.

I'm trying to create an ac$$anonymous$$evement system but the notification is not meant to be sent in real time. I want the player to see what ac$$anonymous$$evement they reached when the scene reloads.

Example: The first ac$$anonymous$$evement is to reach 5 points as $$anonymous$$ghscore. When the player reach that requirement, the value of the ac$$anonymous$$evement is set to true and the "Ac$$anonymous$$evement Unlocked" panel will be activated after the player falls (when the scene loads again).

The problem is: my ac$$anonymous$$evementUnlocked variable reset along with the scene, so I can't save it's value. I don't want to use PlayerPrefs since it's a temporary variable, and I already have so many PlayerPrefs stored (Ac$$anonymous$$evement texts, locked or unlocked, etc).

Here is some code:

 // PlayerPrefs Predef 
     public int $$anonymous$$ghscore;
 
     public int[] ac$$anonymous$$evements= new int[20];
 
 
 // Other variables
 
   bool newAc$$anonymous$$evement= false;
   string tempText;
 
  void Start()
     {
 //...
  $$anonymous$$ghscore = PlayerPrefs.GetInt("Highscore");
 
         for (int i = 0; i < 20; i++)
         {
                 ac$$anonymous$$evements[i] = PlayerPrefs.GetInt("Ac$$anonymous$$evement" + i.ToString());
         }
 
 if (newAc$$anonymous$$evement)
         {
             showPanel();
         }
 //...
     }
 
 void Update()
 {
 testAc$$anonymous$$evements();
 }
 
  public void showPanel()
     {
 
         ac$$anonymous$$evementText.text = tempText;
         myPanel.SetActive(true);
 
 
     }
 
  public void testAc$$anonymous$$evements()
     {
         if ($$anonymous$$ghscore >= 5 && ac$$anonymous$$evements[0] == 0)
         {
             newAc$$anonymous$$evement= true;
             
             tempText= myClass.ac$$anonymous$$evementText[0];
             ac$$anonymous$$evements[0] = 1;
             PlayerPrefs.SetInt("Ac$$anonymous$$evement0", ac$$anonymous$$evements[0]);
         }

 public void resetAc$$anonymous$$evements()
     {
         tempText= " ";
         newAc$$anonymous$$evement= false;
     }

T$$anonymous$$s code isn't my full script, but it have the relevant parts.

I want to be able to check if a new ac$$anonymous$$evement was unlocked, show my Ac$$anonymous$$evement Panel when the scene restarts, set the text in t$$anonymous$$s Ac$$anonymous$$evement Panel to the text associated with my Ac$$anonymous$$vement (stored in myClass), and when the player $$anonymous$$ts the button to go back, the "newAc$$anonymous$$evement" variable will be false, so the game doesn't always show the panel when the game restarts.

How may I store t$$anonymous$$s variable only, so it doesn't set to "false" when the scene reloads? Or is there another way to to t$$anonymous$$s Ac$$anonymous$$evement system the way I want to?