Here are some low-light samples.
Moto G4, auto mode:
The photo is incredibly grainy and basically unusable. It was the best I could get using auto mode without using the flash.
Moto G4, ISO 200, .5s shutter
Better, but still very grainy despite the low manual ISO.
Conclusion: while the Moto G4 takes good daylight photos, its low-light photos are very disappointing.
My Moto G4 got the Nougat update two days ago, but the low-light performance remains the same (which is to say, terrible).
Compare the above to this photo by an even less expensive Microsoft Lumia 640 XL (auto mode; it can do even better in manual mode):