Database notification error Broadcasting [database-notifications.sent] on channels

$agency = User::findOrFail($this->userId);

$agency->notify(
            Notification::make()
                ->success()
                ->title('PDF created!')
                ->body('<a href="'.Storage::url($filename).'" target="_blank" style="text-decoration: none; font-weight:bold; color: green">Download .pdf</a>')
                ->toDatabase(),
        );

[2024-09-18 14:33:41] production.INFO: Broadcasting [database-notifications.sent] on channels [private-App.Models.User.3] with payload:
{
    "user": {
        "id": 3,
        "profile_img_id": null,
        "first_name": "John",
        "last_name": "Doe",
        "rag_sociale": "JohnDoe SRL",
        "email": "[email protected]",
        "email_verified_at": "2024-08-07 12:53:40",
        "is_active": "2024-08-08 20:00:01",
        "privacy_accepted_at": "2024-08-07 19:33:29",
        "casting_country": null,
        "phone_prefix": 39,
        "phone": 12345678,
        "nationality": null,
        "birth_city": null,
        "birth_date": null,
        "fiscal_code": null,
        "created_at": "2024-08-07 12:53:08",
        "updated_at": "2024-08-08 20:00:01"
    },
    "socket": null
}  

...
            ->databaseNotifications()
            ->databaseNotificationsPolling('15s')
...