Drupal 9 has now deprecated PHP 7.4. CiviCRM gives lots of deprecated and warning messages under PHP 8.1. It is possible to suppress them by adding
// PHP 8.1 generates lots of warnings that 7.4 does not. error_reporting(E_ALL & ~E_DEPRECATED & ~E_WARNING);
require_once 'CRM/Core/ClassLoader.php'; CRM_Core_ClassLoader::singleton()->register();
at the bottom of civicrm.settings.php. However, are there plans to change the code so those warnings are no longer given? It is surely better to make sure the code doesn't give deprecated and warning messages?