Sony is one of the few Android OEMs that officially advertise support for unlocking their devices' bootloaders, with the usual warnings, of course. It is, however, to be expected that there would be some kinks here and there. The latest issue is reported to affect the Xperia Z3, which loses its impressive camera quality, as well as access to some pre-loaded content, when users decide to unlock the smartphone's bootloader.
At the heart of the matter is DRM or Digital Rights (some say Restrictions) Management, in particular, DRM security keys that authenticate the device as something unaltered and safe. These DRM keys are apparently used just not to allow viewing of copyrighted media content, which are their most common use case, but also for camera functionality, like proprietary noise reduction algorithms. In effect, this means that quality in low-light situations will be adversely affected. In addition, Sony warns that since the secure user data partition will no longer be accessible, official software updates will no longer be received. Here is Sony's official statement from the updated bootloader unlocking page:
"Certain pre-loaded content on your device may also be inaccessible due to the removal of DRM security keys. For high-end devices running recent software versions, for instance Xperia Z3, the removal of DRM security keys may affect advanced camera functionality. For example, noise reduction algorithms might be removed, and performance when taking photos in low-light conditions might be affected. The secure user data partition may also become inaccessible, and you will not be able to get any more official software upgrades if you unlock the boot loader."
The XDA Forums have a list of confirmed features that won't work after unlocking the bootloader, including the BRAVIA Engine and S-Force Front Surround sound. Reported, but not confirmed, to be also affected are Miracast and MirrorLink features as well as Sony's Entertainment Media apps and content.
This camera issue isn't exactly new to Sony. The Xperia Z1 also suffered quality loss when its bootloader was unlocked and it took almost three months for it to be fixed. Since DRM and highly proprietary technology is involved, it isn't surprising that unlocking the Xperia Z3's bootloader would indeed affect the user's experience. Hopefully, though, Sony will be working on a solution that will satisfy everyone involved and hopefully soon.