Find tags in prefab in unity editing mode

using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using UnityEditor;
using UnityEngine;

public class TestTTTT : EditorWindow
{
    static Dictionary<int, List<GameObject>> layerDic = new Dictionary<int, List<GameObject>>();
    static string findTag = "m_Layer";

    [MenuItem("TestTTTT/ Find references  #&R", false, 10)]
    public static void ShowWindow()
    {
        GetWindow<TestTTTT>(" Find references ").Show();
    }

    private void OnGUI()
    {
        if (GUILayout.Button("Spawn"))
        {
            Find();
        }
    }
    static private void Find()
    {
        string[] paths = AssetDatabase.GetAllAssetPaths();
        // Load all prefab resources 
        var gos = paths.Where(path => path.EndsWith("prefab")).Select(path => AssetDatabase.LoadAssetAtPath<GameObject>(path));
        var sum = 0;
        foreach (var item in gos)
        {
            if (sum >= 10)
                break;

            GameObject go = item as GameObject;
            if (go == null)
            {
                continue;
            }
            //sum++;
            var resPath = AssetDatabase.GetAssetPath(item);
            Component[] cps = go.GetComponentsInChildren<Component>(true);
            List<int> layers = new List<int>();
            var count = 0;
            foreach (var cp in cps)
            {
                if (cp != null)
                {
                    SerializedObject so = new SerializedObject(cp);
                    var property = so.FindProperty(findTag);
                    if (property != null)
                    {
                        var layer = property.intValue;
                        if (!layers.Contains(layer))
                        {
                            layers.Add(layer);
                        }
                    }

                    EditorUtility.DisplayProgressBar(" Find references ", resPath, count++ / (float)cps.Length);
                    //Debug.LogError($"resPath:{resPath} property:[{property?.intValue}]");
                }
            }
            foreach (var layer in layers)
            {
                if (!layerDic.TryGetValue(layer, out var list))
                {
                    list = new List<GameObject>();
                    layerDic[layer] = list;
                }

                if (!list.Contains(item))
                {
                    list.Add(item);
                }
            } 
        }

        Debug.LogError($"Keys:{layerDic.Keys.Count}");
        foreach (var layer in layerDic.Keys)
        {
            Debug.LogError($"layer:{layer}");
        }

        Resources.UnloadUnusedAssets();
        EditorUtility.ClearProgressBar();
    }
}