librex-extra/image_proxy.php

<?php

    $config = require "config.php";
    require "misc/tools.php";

    $url = $_REQUEST["url"];
    $requested_root_domain = get_root_domain($url);

    $allowed_domains = array("qwant.com", "wikimedia.org", get_root_domain($config->invidious_instance_for_video_results));

    if (in_array($requested_root_domain, $allowed_domains))
    {
      $image = $url;
      $image_src = request($image);

      header("Content-Type: image/png");
      echo $image_src;
    }
?>