Hi Cornel,
I'm Cherrelyn and I'm here to help.
Please try to reset or reinstall the Camera app, or just use the built-in QR scanner from the Windows “Quick Settings” menu or your phone instead. That usually happens if the QR scanning feature is turned off or missing after an update.
I hope this will help and if you have any question please feel free to ask.
Warm regards,
Cherrelyn