On my phone, it was an issue of 'Battery saver.' Here is how I made the orange disappear:
1. Go to 'Settings'
2. Scroll down and tap on 'Battery'
3. At the top of that screen, it reads 'Battery saver' Tap on that then it will give you option of switching the 'Battery saver' off. In the future, if you would like to turn it back on, you can easily do that as well.