Modern Drupal is Drupal 8, 9, 10, 11 or above. It is the Drupal of today, with the ability to upgrade in place and powered in part by the Symfony framework. Modern Drupal uses the Twig templating engine. Modern Drupal will not leave your content behind.
Modern Drupal adds major improvements and deprecates old code gracefully.
Modern Drupal is what Agaric does.