Here's my conversation with a Motorola customer support representative:
Jahmila: Hi, my name is Jahmila. How may I help you?
Gabriele: Hello Jahmila. I received my new Moto G a few days ago, everything is fine with it except one thing
Gabriele: with auto brightness disabled, and the slider set to the minimum, I notice slight screen flickering on white backgrounds. When I enable the auto brightness, even in dark rooms, the flickering goes away
Gabriele: With Wi-Fi and 3G disabled it's still the same. I know that KitKat on the Moto G modified the minimum brightness coming from Jelly Bean, wondering if that may have something to do with it.
Jahmila: Does this happen also when using the Chrome browser?
Gabriele: I know about that bug with Chrome, and it's not that flickering
Gabriele: the flickering i'm talking about is like a slight decrease-increase in brightness, it's continuous
Jahmila: Does it happen when the phone is in Safe mode?
Gabriele: hmm didn't try this, how do I reboot it in safe mode?
Jahmila: start the phone up in Safe Mode by pressing the power key then pressing and holding on Power Off, you will then be asked if you want to start the phone up in Safe mode, select OK. Safe mode temporarily disables all 3rd party applications so you can not see them - they have not been deleted. Use the phone in Safe mode without starting or installing any 3rd party apps for 24 hours or until the issue appears again
Gabriele: I can try right now, bare with me for a minute please
Gabriele: so, with the phone off, should I just keep the power button pressed until I have the question about the safe mode?
Jahmila: No. When the phone is on and you press the power key ou get differnt options. Amongst the: Power off? You thn press and hold on power off and will then be asked if you want to boot up in Safe Mode
Gabriele: aha, got it. just a second
Gabriele: yes, it does happen in safe mode too
Gabriele: it looks like the screen is driven by PWM technology, at extremely low brightness that technology can generate flickering
Gabriele: now I enabled auto brightness, i'm in a dark room. The brightness is higher than before, and I don't notice any flickering
Jahmila: my advanced technicians confirm that this is considered manufacturers tolerance meaning that this may occur on a device but is suck a minor issue it is not considered a fault
Gabriele: I know that with the latest software update the minimum brightness of the moto G has been turned up, could it be that Motorola wanted to increase the tolerance?
Jahmila: Yes the brightness has been increased as there were complaints that the brightness was too low
Gabriele: is there any way you could remote the device and check if the value of minimum brightness corresponds to the standard, or if it's too low?
Gabriele: because as we speak, the minimum brightness is very dim on my device. as I turn on auto brightness, it does increase quite a bit
Gabriele: so maybe motorola only tweaked the autobrightness parameter, instead than the manual brightness?
Gabriele: I didn't check if the device had the problem under Android 4.3, as I got updated as soon as I received it.
Jahmila: could be, we really dont have that kind of detailed information on a end user customer service level. i can however confirm that your device does not appear to be faulty and is working as designed. We will of course pass your comments along to the relevant department for future consideration
Gabriele: could I be put in contact to a higher level maybe? in order to discuss this behaviour. Or if you have a Moto G sample around, could you check if you notice flickering at minimum brightness aswell?
Jahmila: We have checked, that is why i could confirm this
Gabriele: ah so you've seen the same?
Jahmila: not on this device , but again, it has been confirmed as a manufacturers tolerance. it is a small pay off to appease a larger volume of customers who were dissatisfied with the brightness previously
Gabriele: so actually there is no way to know if this "brightness adjustment" was applied to the manual brightness or to the auto brightness?
Gabriele: when going from 4.3 to 4.4, I mean.
Jahmila: No, that is correct
Gabriele: it would be interesting to compare a device with 4.3, one with 4.4, set them at the minimum manual brightness and see if they have the same level
Gabriele: if you could come back to me with this information, that would be really helpful
Jahmila: I will escalate your requestbut can not guarantee outcome
Gabriele: ok, thank you in advance for that
Jahmila: thank you for contacting Motorola and taking the time to provide your comments. Is there anything else I can help you with at this time?
Gabriele: no thank you
Gabriele: have a good day!
Jahmila: Thank you, the same to you, bye!