gather-and-defend/Assets/Scripts/General/SingletonSO.cs

using UnityEngine;

public class SingletonSO<T> : ScriptableObject where T : SingletonSO<T>
{
    private static T _instance;
    public static T Instance
    {
        get
        {
            if (!_instance)
            {
                _instance = CreateInstance<T>();
            }
            return _instance;
        }
    }
}