Random animated string (see https://www.reddit.com/r/programming/y13q8x )

Program.cs

// Use chars from input value with custom iterations
WriteAnimatedString("Hello world", 50);
Console.WriteLine();

// Use printable ASCII chars with left-to-right effect
var chars = Enumerable.Range(32, 127).Select(c => (char)c);
WriteAnimatedString("I learned something new today!", animationStyle: AnimationStyle.LeftToRight, chars: chars);
Console.WriteLine();

static void WriteAnimatedString(
    string value,
    int maxiterations = 200,
    TimeSpan? sleep = null,
    AnimationStyle animationStyle = AnimationStyle.Random,
    IEnumerable<char>? chars = null)
{
    // Input validation
    ArgumentNullException.ThrowIfNull(value, nameof(value));
    if (maxiterations <= 0)
    {
        throw new ArgumentOutOfRangeException(nameof(maxiterations));
    }

    if (sleep < TimeSpan.Zero)
    {
        throw new ArgumentOutOfRangeException(nameof(sleep));
    }

    // Initialization and setup
    var rng = new Random(42);                                   // Random number generator with fixed seed so animations are deterministic
    var currentchars = value.Select(c => ' ').ToArray();        // Initialize a char array of same length as input with spaces
    var counters = Enumerable.Range(0, value.Length)            // Initialize letter counters
        .Select(i => animationStyle switch
        {
            AnimationStyle.SingleShot => maxiterations,                                                                     // All counters same value
            AnimationStyle.LeftToRight => (int)Math.Ceiling((i + 1) * (maxiterations / (double)value.Length)),              // Ascending counters
            AnimationStyle.RightToLeft => (int)Math.Ceiling(maxiterations - (i * (maxiterations / (double)value.Length))),  // Descending counters
            AnimationStyle.Random or _ => rng.Next(maxiterations)                                                           // Random counters
        }).ToArray();
    var rndchars = (chars ?? value.Select(c => c))
        .Distinct().ToArray();                                  // Initialize available chars (when none specified, use inputstring as source)
    sleep ??= TimeSpan.FromMilliseconds(10);                    // Default sleep to 10 ms is not specified
    var (cp_left, cp_top) = Console.GetCursorPosition();        // Get cursor position before we do anything

    // Go time!
    Console.CursorVisible = false;                              // Hide cursor
    while (!currentchars.SequenceEqual(value))                  // Keep going until currentchars equals input value
    {
        Console.SetCursorPosition(cp_left, cp_top);             // Return cursor to position where we first found it at
        Thread.Sleep(sleep.Value);                              // Slow down 'animation'
        for (var i = 0; i < value.Length; i++)                  // Randomize string by iterating each letter
        {
            currentchars[i] = --counters[i] <= 0                // Decrease counter, then when at 0 or less...
                ? value[i]                                      // ...pick actual letter from string
                : rndchars[rng.Next(rndchars.Length)];          // ...else pick random letter
        }

        Console.Write(currentchars, 0, currentchars.Length);    // Output string
    }
    Console.CursorVisible = true;                               // Show cursor
}

public enum AnimationStyle
{
    Random = 0,
    SingleShot = 1,
    LeftToRight = 2,
    RightToLeft = 3