Hi Oussama,
That's interesting, we have not had any reported issues of QR codes not working on Windows, or seen any issues with all our test devices. I just did more tests with the 3.10 release builds on Windows 10 (Surface Book) and QR code scanning working as expected.
What version of Windows are you using? Can you provide exact Edition, Version and OS build number from System About screen in Windows Settings.
Also can you confirm the device make and model?
If you install the 3.9 builds again, does the QR code scanning work as expected?
Are you able to share a copy/image of the QR code you are trying to scan?
And as a last test, can you see if you can scan this QR code below from a printed copy or even from the screen using your Windows device with 3.10 builds.
Regards,
Phil.