Yes. If you change the production domain in your branding section, all created QR Codes continue to work. Both domains - the old and the new one - will work. However, dynamic QR Codes that are already printed, will contain the old domain, because the shortened URL of a printed QR Code cannot be changed.
You can also setup up a production domain for each user in your white label account. However, once a custom user domain is changed, QR Codes that contain the previous domain for that user will not work anymore.