Error when creating new guestbook

Hello, I got this error in the backend when creating a new guestbook: 
Deprecated: KubikRubik\Component\EasybookReloaded\Administrator\Controller\GuestbookController::__construct(): Implicitly marking parameter $factory as nullable is deprecated, the explicit nullable type must be used instead in ...

And when viewing the dafault guestbook in the frontend:
Deprecated: KubikRubik\Component\EasybookReloaded\Site\Controller\DisplayController::__construct(): Implicitly marking parameter $factory as nullable is deprecated, the explicit nullable type must be used instead in

Joomla: 5.4.3
PhP 8.4
EBR: 5.1.2.0-PRO

Could you help me please?
Kind regards, Peter

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