Custom editor values set in prefab editor not set in prefab asset

Hello everyone. I have made a prefab House with a GridModel component added to it. I have written a custom editor for it, but for some reason when I edit the variable in the Prefab Mode inspector, the changes aren't applied to the prefab in the Project window and vice versa. How can I solve this issue?

GridModel.cs

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

GridModelEditor.cs

 [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);
     }
 }