Download actual favicon with https://github.com/ArthurHoaro/favicon

get_favicon

<?php
stream_context_set_default(array(
  'http' => array(
     'method' => 'GET',
     'timeout' => 10,
     'header' => "User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:20.0; Favicon; +https://github.com/ArthurHoaro/favicon) Gecko/20100101 Firefox/32.0\r\n",
   )
 )
);

/**
* Get feed favicon
*/
$favicon = FAVICON_DIRECTORY . $feed_name . '.ico';
if( (!file_exists($favicon) ) {
  $favService = new Favicon();
  if( $favUrl = $favService->get($feed_link) ) {
    $favRequest = file_get_contents($favUrl);
    file_put_contents($favicon, $favRequest['html']);
  }
}
  
if( !file_exists($favicon) || !filesize($favicon) ) {
  copy( FAVICON_DIRECTORY . FAVICON_DEFAULT, $favicon );
}