C# method to validate a Telegram username using RegEx

ValidateTelegramUsername.cs

using System;
using System.Text.RegularExpressions;

// NOTE: Change min length to 4 (instead of 5) in the RegEx if you want to include/allow NFT/Fragment usernames
bool ValidateTelegramUsername(string username)
    => Regex.IsMatch(username.TrimStart('@'),
        @"^(?=.{5,32}$)(?!.*__)(?!^(telegram|admin|support))[a-z][a-z0-9_]*[a-z0-9]$",
        RegexOptions.IgnoreCase | RegexOptions.Compiled);
        
Console.WriteLine(ValidateTelegramUsername("Laiteux1")); // True
Console.WriteLine(ValidateTelegramUsername("1Laiteux")); // False: Must start with a letter
Console.WriteLine(ValidateTelegramUsername("Lait")); // False: Too short (must contain between 5 and 32 characters)
Console.WriteLine(ValidateTelegramUsername("_Laiteux_")); // False: Starts or ends with an underscore
Console.WriteLine(ValidateTelegramUsername("Lait__eux")); // False: Contains two or more consecutive underscores
Console.WriteLine(ValidateTelegramUsername("AdminLaiteux")); // False: Starts with "Telegram", "Admin" or "Support"