Originally Posted by deadlocked007
I have the 900t and in the dark my camera has a purple tint at the corners
It's hard to be certain because you only posted a single, low resolution image. But it's probably chromatic aberration. This is a type of distortion that occurs when component colours do not focus at the same convergence point. The misregistration of red and blue is seen as purple banding. You will also see this in SLR lenses that cost three times as much as the S5. The perfect lens (or image sensor) is an elusive goal.
Nor is this unique to the S5. Lots of people complained about something similar in the Apple 5s.
All cameras have various limitations. The S5 camera is superior in bright light and weak in low light. That is simply a design tradeoff. Your phone is only defective if you have markedly more artifacts than other S5's. And there is little in this particular picture to suggest that is the case.
If it you really find it intolerable, then return or sell your S5 and buy a different model. But realize that any other phone will have image defects as well. Just in some other visual aspect.