Hi DragosLicar,
Thank you for reaching Microsoft Community. We're sorry for the trouble this has caused you. I appreciate the time you have spent in trying to resolved this issue. Let me help you on this.
What device was your Slim pen 2 pair with?
What build version of Windows 11 are you on?
Any changes made before this issue happens?
Try to uninstall the Microsoft Bluetooth LE Enumerator under Bluetooth in Device Manager.
Let me know how it goes.
Kind regards,
Lavenia