After "Restarting/Reloading" a level, I have multiple pause screens.

@cat_dawg I think what you said is problably the reason for you to having multiple instances of the same object, since when you load a scene it will instatiate all the objects belonging to it and bring over all objects that are tagged dont destroy on load from the current scene.

The most likely solution to your problem is to check if a instance of that object already exists and if so destroy it.

You can do that with the following lines of code:

 private static YourClassName Instance;
 
     private void Awake()
     {
         if (Instance != null)
         {
             Destroy(gameObject);
         }
         else
         {
             Instance = this;
         }
     }