Undo.RecordObject doesn't record array

Undo.RecordObject doesn't writes array, so when I press ctrl+z, variable count changes, but array not. Is it okay?

It is simplified example, not real code. Component with variable and array of objects:

  public class DataHolder : MonoBehaviour {
     [SerializeField] public Data[] array = new Data[0];
     [SerializeField] private int count;
 
     public void Reset() {
         array = new Data[0];
         count = 0;
     }
 
     public void AddData() {
         Array.Resize(ref array, array.Length + 1);
         array[array.Length - 1] = new Data();
 
         count++;
     }
 }

In ideal world, count always equals array.Length. But undo operation violates this invariant :( I tried to record whole game object instead of dataHolder, but it doesn't work too.

 [CustomEditor(typeof(DataHolder))]
 public class HolderInspector : Editor {
     public override void OnInspectorGUI() {
         DrawDefaultInspector();
 
         var dataHolder = target as DataHolder;
 
         if (GUILayout.Button("add Data")) {
             Undo.RecordObject(dataHolder, "add data");
             EditorUtility.SetDirty(dataHolder);
 
             //Undo.RecordObject(dataHolder.gameObject, "add data");
             //EditorUtility.SetDirty(dataHolder.gameObject);
 
             dataHolder.AddData();
         }
 
         GUILayout.Label("array size = " + dataHolder.array.Length);
     }
 }

and simple class (really it has a lot of data)

 public class Data {
     [SerializeField] public int value;
 }

Is it normal? How can I save data? I really want to use Undo feature.