I am using FuelSDK-CSharp to extract data from SFMC for that I am using the below Code

static void Main(string[] args)
{
try
{
    // Initialize the ETClient
    ETClient client = new ETClient();

    // Retrieve Email Events
    Console.WriteLine("Retrieving Email Events...");
    RetrieveEmailEvents(client);

    // Retrieve SMS Events
    Console.WriteLine("Retrieving SMS Events...");
    RetrieveSMSEvents(client);

    // Retrieve WhatsApp Events
    Console.WriteLine("Retrieving WhatsApp Events...");
    RetrieveWhatsAppEvents(client);
}
catch (Exception ex)
{

    throw ex;
}
}

Getting System.Net.WebException: ‘The remote server returned an error: (400) Bad Request.’ error when trying to Initialize the ETClient, below is the config I am using

    <?xml version="1.0" encoding="utf-8"?>
<configuration>
  <configSections>
    <section name="fuelSDK" type="FuelSDK.FuelSDKConfigurationSection, FuelSDK" />
  </configSections>
    <startup> 
        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.8.1" />
    </startup>
  <fuelSDK appSignature="none" clientId="abc" clientSecret="cdf" 
           authEndPoint="https://<subomain>.auth.marketingcloudapis.com/v1/requestToken" 
  restEndPoint="https://<subomain>.rest.marketingcloudapis.com/" />
</configuration>

Please point me in the right direction to solve the issue