using System;

using System.Globalization;

public class Program

{

    public static void Main()

    {

        var horribleTimestamp = "20220505   17:36:29";

        var timestamp = DateTime.ParseExact(horribleTimestamp, new[]{"yyyyMMdd HH:mm:ss","yyyyMMdd  HH:mm:ss","yyyyMMdd   HH:mm:ss"}, CultureInfo.InvariantCulture, 0);

        Console.WriteLine(timestamp);

    }

}