morsok

 use Drupal\Core\Url;
 use Symfony\Component\HttpFoundation\Request;
 
 function my_function() {
  $previousUrl = \Drupal::request()->server->get('HTTP_REFERER');
  $fake_request = Request::create($previousUrl);
  $url_object = \Drupal::service('path.validator')->getUrlIfValid($fake_request->getRequestUri());
  if ($url_object) {
    $route_name = $url_object->getRouteName();
    // Do something with $route_name;

luksak

<?php

namespace Drupal\MODULE\EventSubscriber;

use Drupal\commerce_order\Entity\Order;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Drupal\commerce_cart\Event\CartEntityAddEvent;
use Drupal\commerce_cart\Event\CartEvents;
use Drupal\Core\StringTranslation\StringTranslationTrait;
use Symfony\Component\HttpKernel\Event\GetResponseEvent;