Why does the value of the public property of [Serializable] class persist in ScriptableObject between Editor runs ?

I have a class like this

 [Serializable]
 public class Team
 {
     public string Name;
     public int NumberOfPlayers { get; set; }
 }

and I have a ScriptableObject class like this

 public class GameSettings : ScriptableObject
 {
     public Team[] Teams = new Team[2];
 }

when the instance of the GameSettings is selected in the Editor, in Inspector panel I can edit (as expected) only the Name field of each Team instance. Then, when the game is running, I change the values of the NumberOfPlayers properties via code, and to my surprise, these values are kept between runs of the game in the Editor.

IOW when I stop a game running in the editor and start it again, these values are not 0 (as I expect them to be since they are properties and, as I understand, shouldn't be serialized and saved especially when the game is running).

Having a property in ScriptableObject to keep values during the game probably is not the best approach but the question is still why and where the values are kept?

I checked the GameSettings.asset and there is no such value/name serialized, neither I could find it in other files within the project folders.