TypeError on send email

When sending an email via Email API as an action of a CiviRule I get the error:

TypeError: strtolower(): Argument #1 (closed) ($string) must be of type string, array given in strtolower() (Line 1408 von /var/www/foo/web/sites/all/modules/civicrm/CRM/Core/DAO.php).

It seems to be caused by the token replacement process in order to send the email. The contact ID is passed as an array instead of a string.

System Environment
PHP: 8.0.19
Email API: 2.8
CiviCRM: 5.50.2
CiviRules: 2.43
Drupal: 7.90