public static void Main(string[] args)
string filename="f6600af200.ext.230106.2";
string dateFromFilename = filename.Split('.')[2];
string asOfDate = DateTime.ParseExact(dateFromFilename, "yyMMdd", System.Globalization.CultureInfo.InvariantCulture).ToString("yyyy-MM-dd HH:mm:ss.fff");
Console.WriteLine(dateFromFilename);
Console.WriteLine(asOfDate,"\n");