dark shades appears on screen on iphone 6s

Hi GoldenStag,

It sounds like you are saying the screen goes to a darker shade when you open some mail app, that the screen is not as bright.

If this is happening with just that mail app then you can focus on it's settings or troubleshoot that app.

If an app you installed unexpectedly quits, stops responding, or won’t open - Apple Support

For example, check for app updates or delete and reinstall the app.

If it happens with other apps as well, see

Get help with the screen on your iPhone, iPad, or iPod touch - Apple Support

If your screen is too dim, too bright, or you see only faint images

1. Try to adjust the brightness. If the screen doesn’t respond when you adjust the brightness, open several apps to make sure it’s not an issue with only one app.
2. If you have a screen protector, try removing it. Try removing your case if it includes a screen protector.
3. If you see the issue in multiple apps, restart your device.
4. If restarting doesn’t fix the issue, restore your device.
5. If you still see the issue after you restore, contact Apple Support.

Thank you for using Apple Support Communities.