Trecho método obrigado por sua compra - Curso Symfony 5 Mastery - http://codeexperts.com.br

CheckoutController.php

<?php
  //...
  /**
	 * @Route("/checkout/thanks", name="home_checkout_finished", priority="10")
	 * @IsGranted("ROLE_USER")
	 */
	public function thanks(Request $request)
	{
		$session = $request->getSession();

		$cart = $session->get('cart');

		if($session->has('cart')) {
			$session->remove('cart');
		}

		return $this->render('thanks.html.twig', compact('cart'));
	}