Iphone XS camera flickering

We've bought 2 iphone xs 256gb (let's name them iphone A (good) and iphone B (bad)).

Tested both side by side and found out that:

1. iphone B has worse detalization of selfie camera over iphone A

2. iphone B camera flickering effect takes place where iphone A looks good and works without problems. Flickering is for both rear and selfie. Flickering effect takes place for iphone B even in photo mode. Please take a look at video.

Video example: Dropbox - IMG_5436.MOV

Left: Iphone A - good

Right: Iphone B - not good

What I've tried to fix the problem:

1. Hard reset

2. Restore via DFU

3. Restore to 12.0.1 to check how selfies differ - the same issue with camera on B

4. Update from 12.0.1 to 12.1 - didn't help

Didn't help at all. Flicker effect remains.

Apple please let us know asap what to do, since phones are at high prices and what I see is not what I expect for this price at all. And we don't have apple store in our country.

Thanks!