RouteSubscriber.php

<?php

declare (strict_types=1);
namespace Drupal\user_route_alter_test\Routing;

use Drupal\Core\Routing\RouteSubscriberBase;
use Drupal\Core\Routing\RoutingEvents;
use Symfony\Component\Routing\RouteCollection;

/**
 * Alter the 'user.pass.http' route.
 */
class RouteSubscriber extends RouteSubscriberBase {
  
  /**
   * {@inheritdoc}
   */
  protected function alterRoutes(RouteCollection $collection) : void {
    if ($route = $collection->get('user.pass.http')) {
      $route->setRequirements([]);
      $route->setRequirement('_access', 'FALSE');
    }
  }
  
  /**
   * {@inheritdoc}
   */
  public static function getSubscribedEvents() : array {
    $events = parent::getSubscribedEvents();
    // Ensure this event is triggered before
    // \Drupal\serialization\EventSubscriber\UserRouteAlterSubscriber.
    $events[RoutingEvents::ALTER] = [
      'onAlterRoutes',
      1,
    ];
    return $events;
  }

}