Code using facebook php sdk stopped working suddenly – what happened?

I have an old piece of php code calling Facebook, that used to work fine until a week ago. Now it suddenly stopped working. Here are the relevant lines involved:

<?php
require_once __DIR__ . '/facebook-sdk-v562/autoload.php';

// -- skipping here less relevant lines --

// Initialize Facebook Environment:
$default_graph_version = 'v2.10';
$fb = new Facebook\Facebook([
  'app_id' => $app_id,
  'app_secret' => $app_secret,
  'default_graph_version' => $default_graph_version
]);

// Redirect to phase2 for facebook login:
$helper = $fb->getRedirectLoginHelper();
$fbPermissions = ['manage_pages', 'publish_pages'];
$loginUrl = $helper->getLoginUrl($phase2_url, $fbPermissions);
header('Location: ' . $loginUrl);

Now upon reaching the header line, I get: “Sorry, something went wrong. We’re working on getting this fixed as soon as we can.” — I have a feeling (not sure) it has to do with using old versions of things? Has something changed in the recent days (May 2022)?

EDIT:
I’ve made certain updates in order to match new Graph API version. I used compose to download the new php sdk, I modified the require_once accordingly, and I modified v2.10 to v13.0. I still get the exact same error.
I checked the value of $loginUrl that gives me the error after redirection, and it is (shortened): https://www.facebook.com/v13.0/dialog/oauth?client_id=[***]&state=[***]&response_type=code&sdk=php-sdk-5.7.0&redirect_uri=[my correct url]&scope=manage_pages%2Cpublish_pages