Currently have an issue were we have a Drupal 7 Website running fine but have create a microsite to sit under /d8 of the drupal 7 website. We run this through a nginx reverse proxy which is fine but the issue I am having is that instead of the paths to images being /d8/sites/default/files it renders out as /sites/default/files so it attempts to use d7 proxied site files (same with the theme assets it goes to /themes/custom instead of /d8/themes/custom

Is there a way to set the drupal 8 url generate to include the prefix?