Changes into in Joomla\Http\Http in Joomla! 4.0?

Question

I have a part of code in my componenent which works in Joomla! 3.9.x, but in Joomla! 4.0-beta-dev i get a 503 error. My code is the following :

use Joomla\Http\Http;
use Joomla\Http\Transport\Stream as StreamTransport;

public function sendtostopforumspam()
{
 $options = array();

 $transport = new StreamTransport($options);

 $http = new Http($options, $transport);

 $data = array('username' => $username, 'ip_addr' => $ip, 'email' => $email, 'api_key' => $key);

 $response = $http->post('https://www.stopforumspam.com/add', $data);

 if ($response->code == '200')
 {
  // do something...
 }
}

In the response i can see an error 503

What are changes in Joomla! 4.0 which prevent that working ?

Thanks by advance