using System;

public class Program

{

    public static void Main()

    {

        string text = "AFN3oCJ7IlRleHQiOiLDoGFhIiwiU2VxIjoxLCJNYXgiOjYwMDB9";

        System.Text.Encoding[] encoders = [

            System.Text.Encoding.UTF8, 

            System.Text.Encoding.Latin1, 

            System.Text.Encoding.ASCII, 

            System.Text.Encoding.Unicode,

            System.Text.Encoding.BigEndianUnicode,

            System.Text.Encoding.Default,

            System.Text.Encoding.UTF7

        ];

        byte[] bytes = Convert.FromBase64String(text);

        foreach(var encoding in encoders)

        {

            string encodedText = encoding.GetString(bytes);

            Console.WriteLine($"{encoding.EncodingName}: {encodedText} {Environment.NewLine}");

        }       

    }

}

​