This message appears above all Joomshopping entries in the backend.
Even with system error display and debugging disabled.
I think it started with the installation of vendor frontend addon.
Deprecated: Joomla\Component\Jshopping\Administrator\Controller\BaseadminController::__construct(): Implicitly marking parameter $factory as nullable is deprecated, the explicit nullable type must be used instead in /home/.sites/91/site297/web/sb_webseite/administrator/components/com_jshopping/Controller/BaseadminController.php on line 25
If I understood you right in the past, it's just a message and no error. But as it is present in all views, it's a little bit disturbing.
