Q: Moon shape on front camera gold iPhone 6 16gb

It means that you have the Do Not Disturb option enabled. You can turn it off by swiping up to display the Control panel, and then tap on the little crescent moon icon in the top row. Here's a support article that explains how it works:

Use Do Not Disturb on your iPhone, iPad, or iPod touch - Apple Support

Cheers,

GB

This is a known issue with some iPhone 6 front-facing iSight cameras.

http://www.dailydot.com/technology/iphone-6-camera-shift-problem/

From what I understand it won't affect the quality or cause issues with taking pictures but if it bothers you then you can take it to an Apple Store and they will replace it. I would assume that it would still need to be under warranty for a replacement but check with Apple to be sure.

The iPhone 6 was released September 2014 so it's nearing a year and a half. The iPhone 6s was released September 2015. As far as I know, only the iPhone 6 was affected. I haven't heard any people that have said they have seen the issue with an iPhone 6s.

is there anything from Apple that says this is a known issue?

Apple has never officially come out with a statement regarding the issue.

However, search these forums and online and you will find a lot of people have had the problem.