MaterialPropertiesPreserver.cs

using System.Collections.Generic;
using UnityEngine;

namespace Apkd
{
    namespace Internal
    {
        sealed class MaterialPropertiesPreserver : MonoBehaviour
        {
#if UNITY_EDITOR
            public static MaterialPropertiesPreserver Instance;
            readonly Dictionary<Material, Material> originalMaterials = new Dictionary<Material, Material>();

            internal void Register(Material material)
            {
                if (!originalMaterials.ContainsKey(material))
                    originalMaterials[material] = Instantiate(material);
            }

            void OnDestroy()
            {
                foreach (var kvp in originalMaterials)
                    kvp.Key.CopyPropertiesFromMaterial(kvp.Value);
            }

            [RuntimeInitializeOnLoadMethod(RuntimeInitializeLoadType.BeforeSceneLoad)]
            static void Initialize()
            {
                Instance = new GameObject(nameof(MaterialPropertiesPreserver)).AddComponent<MaterialPropertiesPreserver>();
                Instance.gameObject.hideFlags = HideFlags.HideAndDontSave;
                DontDestroyOnLoad(Instance.gameObject);
            }
#else
        internal void Register(Material material) { }
#endif
        }
    }

    public static class ExtensionMethods
    {
        public static void PreserveProperties(this Material material)
            => Internal.MaterialPropertiesPreserver.Instance.Register(material);
    }
}