UndestroyableUtility.cs

using System.Collections.Generic;
using UnityEngine;
 
namespace SCG.SpaceAdMobile
{
    [DisallowMultipleComponent]
    [DefaultExecutionOrder(-1)]
    public class UndestroyableUtility : IdentifierUtility
    {
        private static readonly Dictionary<string, Transform> instances = new();
 
        [Tooltip("Enable to preserve this object across scene changes.")]
        [SerializeField]
        private new bool enabled = true;

        public bool IsDestroyed { get; private set; }

        protected virtual void Awake()
        {
            if (!enabled)
                return;
 
            if (instances.TryGetValue(Id, out var existing))
            {
                // A null result indicates the other object was destroyed for some reason
                if (existing != null)
                {
                    if (ReferenceEquals(transform, existing))
                        return;
                    Destroy(transform.gameObject);
                    // Return to skip the following registration code
                    return;
                }
            }
 
            // The following code registers this Transform regardless of whether it's new or replacing
            instances[Id] = transform;
            if (transform != transform.root)
            {
                transform.SetParent(null);
            }
            DontDestroyOnLoad(transform);
        }

        protected virtual void OnDisable() => IsDestroyed = gameObject.activeInHierarchy;

        protected virtual void OnApplicationQuit() => instances.Clear();
    }
}