Metatags for Page Manager pages were disappeared

Definitely need to add more test coverage to cover more scenarios, as something's not quite right.

I'm not positive this is the same issue because I'm not running 2.x, but my page manager metags went missing updating to 4.0-rc3 because of this: https://www.drupal.org/project/page_manager/issues/3362561 🐛 Path has unnecessary query appended. Fixed

if ($variant = $route_match->getParameter('page_manager_page_variant')) {
    return $variant;
  }

The `page_manager_page_variant` variant no longer exists.

There is a patch here 🐛 Update Page Manager integration for latest version Active but it doesn't help me.