IPhone 15 Pro slightly changing screen color, screen tint, uneven brightness

Everytime I am using my iPhone 15 Pro, I am experiencing an issue where my phone's screen slightly changes color. It is becoming more and more noticeable the longer I have noticed it being an issue.

Before I explain further, I would like to mention: True Tone ,Night Shift, dark modus and color filters are turned off.

The issue is very noticeable in the morning when the IPhone us used for the first time in the morning. The screen tint with a white background is too red and the brightness is lower at the bottom of the screen.

After using the phone for some time it improves slightly .

The issue is also influenced by the screen brightness and the picture content. In the evening when the screen brightness is going down the red tint and the uniformity issue is appearing again.

I've read an article where the automatic calibration of IPhone Oled screens was explained. It seems that this mechanism is not always working well and the screen calibration becomes inaccurate. On the internet and on this forum similar behavior was described with other Oled IPhones starting from the IPhone 12.