WSOD when using Test Authentication Sources

I am running Drupal 10.2.3 with drupalauth4ssp 2.0.0-rc1 and simpleSAMLphp v2.1.2 with drupalauth/simplesamlphp-module-drupalauth 2.10.0-rc.1

Some SP work just fine, some give me the following error. This error also appears when I try to test the "drupal-userpass" authentification source from within simpleSAMLphp

Declaration of Drupal\\Component\\EventDispatcher\\ContainerAwareEventDispatcher::addListener($event_name, $listener, $priority = 0) must be compatible with Symfony\\Component\\EventDispatcher\\EventDispatcherInterface::addListener(string $eventName, callable $listener, int $priority = 0): void in /var/www/html/core/lib/Drupal/Component/EventDispatcher/ContainerAwareEventDispatcher.php on line 217; PHP message: Symfony\\Component\\ErrorHandler\\Error\\FatalError: Compile Error: Declaration of Drupal\\Component\\EventDispatcher\\ContainerAwareEventDispatcher::addListener($event_name, $listener, $priority = 0) must be compatible with Symfony\\Component\\EventDispatcher\\EventDispatcherInterface::addListener(string $eventName, callable $listener, int $priority = 0): void in /var/www/html/core/lib/Drupal/Component/EventDispatcher/ContainerAwareEventDispatcher.php on line 217 #0 {main}', referer: https://xxx/module.php/admin/test