Screen Going to Full Brightness with QR Codes

I have several apps - McDonald's, KFC, Subway amongst them - that as soon as you display a QR Code for scanning it changes screen brightness to 100%. This may be OK when you're using it - but it's totally annoying if you happen to display the QR Code in a dimly lit room at home - which is easy to do by accident in some apps. Is there any way to stop the phone doing this, apart from just not using the apps anymore?

I don't know when this 'feature' was introduced and I know it's to make sure codes can be scanned - but there should be a way to manually disable it.