Washed out screen after screen replacement

I have an iPhone 5C that was brought in because of white vertical lines on the screen. After swapping the screen, the new screen looks 'washed out', like it can't produce enough black.

Only the top ( about 0,5 cm) shows the normal colors with decent black. But all the rest of the screen is 'washed out'. I tried 2 more other screens: the second one same issue as the first one. And the third one ( other brand) is the other way around: that one is too dark...

Anyone got an idea? The original screen still shows the white lines.

Also tried another battery, but that didn't help.

Thanks

I also notice the icons were visible when booting(??). And when booted, if I went to another page, I could see a shadow remain of the icon of the previous page. Very strange.

I received 2 new screens yesterday and both screens showed problems again. The supplier said it could be related to a defect to the backlight controller.

However the device is still in warranty for 3 weeks, so we'll try warranty first.

But it's probably not related to the displays. 5 bad screens seems very unlikely.