I have a prefab with a custom GridModel component which has a custom editor. For some reason whenever I edit a value in Prefab Mode, the value doesn't save in the prefab asset and vice versa. How can I fix this issue?

Here is my code:

public class GridModel : MonoBehaviour, IGridModel
{
    public Vector2Int dimensions;
}

[CustomEditor(typeof(GridModel))]
public class GridModelEditor : Editor
{
    private GridModel gridModel;

    void OnEnable()
    {
        gridModel = (GridModel)target;
    }

    public override void OnInspectorGUI()
    {
        gridModel.dimensions = EditorGUILayout.Vector2IntField("Size", gridModel.dimensions);
    }
}