I made some progress, if I paste the request url in a browser, I get the modified response, but if I launch the software i'm tryna bypass it's not modifing the response, or dunno. Fiddler everywhere can't even see the process's request, but http debugger pro does.

here's my code, am I doing something wrong?

using System;
using System.Text;
using System.Threading.Tasks;
using Fiddler;
 
namespace FiddlerCore_ModifyResponse
{
    class Program
    {
        static async Task Main(string[] args)
        {
          
            FiddlerApplication.Prefs.SetBoolPref("fiddler.certmaker.bc.Debug", true);
 
            BCCertMaker.BCCertMaker certProvider = new BCCertMaker.BCCertMaker();
            CertMaker.oCertProvider = certProvider;
            FiddlerApplication.ResponseHeadersAvailable += FiddlerApplication_ResponseHeadersAvailable;
 
            Fiddler.FiddlerApplication.BeforeResponse += FiddlerApplication_BeforeResponse;
            
 
        
 
            FiddlerCoreStartupSettings startupSettings =
                                            new FiddlerCoreStartupSettingsBuilder()
                                                .ListenOnPort(8887)
                                                .DecryptSSL()
                                                .RegisterAsSystemProxy()
                                                .Build();
 
 
            FiddlerApplication.Startup(startupSettings);
            Console.WriteLine("\nPROXY set, waiting for request");
            Console.WriteLine("enter to remove proxy");
 
            Console.ReadLine();
            FiddlerApplication.Shutdown();
        }
 
 
        private static void FiddlerApplication_BeforeResponse(Session oSession)
        {
 
          
 
 
            if (oSession.fullUrl.Contains("xyz"))
            {
                oSession.bBufferResponse = true;
                oSession.utilDecodeResponse();
 
               
                oSession.utilDecodeResponse();
                var oBody = System.Text.Encoding.UTF8.GetString(oSession.responseBodyBytes);
               
                oBody = "522b349923da5dc131887d";
               
                oSession.utilSetResponseBody(oBody);
            }
  
        }
 
        
 
        private static void FiddlerApplication_ResponseHeadersAvailable(Session oSession)
        {
 
            if (oSession.fullUrl.Contains("xyz"))
            {
                oSession.bBufferResponse = true;
            }
        }
    }
}