Holy crap you made me see my p7p in a new light literally because I had to shine a torchlight directly on the screen to see the under display artifact you talking about in the top right corner.
It looks almost like got under display sensor or something opaque there.
But what exactly was told to you by the engineer at the service center about what it is and it's function, and how/who to file a report with for an issue which will only possibly show up down the line?
If I never shine a torchlight on the screen I will never know about it sia... You might be the world's first to discover this feature.