How to fix black loading screen at turn on iphone?

So, I've had this problem on my old iPhone six, and now on my iPhone 7 Plus, and I'd love to have a fix.

I'm on iOS 10.3.1

So, let me explain; When I open my phone, say when I receive a message, I try to unlock it, I get the screen you see in the added picture (I hope, if not, it's a black screen with a white loading circle in the middle).

This doesn't last long, it's like ~5 seconds.

I also know that it gives me the haptic feedback that I'm charging after it's gone (when I have it plugged into a charger).

Is there any way to fix this?

(Posted in iPhone Hardware because I am not sure what community this should be in)