RemoveAll Bug.cs

internal class Program
{
    private static void Main(string[] args)
    {
        List<Soldier> soldiers = new List<Soldier>()
        {
            new Soldier(10),
            new Soldier(0),
            new Soldier(0)
        };

        Print(soldiers);

        Console.WriteLine("----------");
        RemoveAll(soldiers);

        Print(soldiers);
    }

    private static void RemoveAll(List<Soldier> soldiers)
    {
        for (int i = 0; i < soldiers.Count; i++)
        {
            if (soldiers[i].IsAlive == false)
            {
                soldiers.RemoveAt(i);
            }
        }
    }

    private static void Print(List<Soldier> soldiers)
    {
        foreach (var item in soldiers)
        {
            Console.WriteLine(item);
        }
    }
}

class Soldier
{
    private int _health;

    public Soldier(int health)
    {
        _health = health;
    }

    public bool IsAlive => _health > 0;

    public override string ToString()
    {
        return $"Health: {_health}";
    }
}