Hi @igor,

Please put the following  code in the functions.php file of the active theme:

add_filter('comment_text', function ($content, $comment, $args = []) {
   $wpdiscuz = wpDiscuz();
if ($wpdiscuz->isWpdiscuzLoaded) {
   $content = preg_replace_callback('@src\s*=\s*"(.+?)"@is', function ($matches) {
   $file = get_headers($matches[1], 1);
   return 'src="data: ' . $file['Content-Type'] . ';base64,' . base64_encode(file_get_contents($matches[1])) . '"';
   }, $content);
}
return $content;
}, 999, 3);

Please don't forget to delete all caches and press CTRL+F5(twice) on the frontend before checking.

Also please note the code provided above will change all images as you describe in the post above.