DifficultyTracker.cs
using Sandbox;

public sealed class DifficultyTracker : Component
{
	public static DifficultyTracker Instance { get; private set; }

	public int Difficulty { get; set; }

	protected override void OnAwake()
	{
		base.OnAwake();

		Instance = this;

		Difficulty = Math.Clamp((int)Sandbox.Services.Stats.LocalPlayer.Get( "selected_difficulty" ).LastValue, Manager.MinDifficulty, Manager.MaxDifficulty);

		GameObject.Flags |= GameObjectFlags.DontDestroyOnLoad;
	}
}