I have *exactly* the same issue on my q800t. What I see when I see the issue your pictures show is a grid of cells, where the center is darker than the edge. I called support about 2 weeks ago, but my phone (galaxy fold) seemingly couldn't capture it at the time, because as you say, it's subtle... At any rate, in "pro" mode, I could max out the contrast on my phone's camera, and it became visible in photo... I just took pictures today... I think my grid is tighter (smaller cells) than yours, but same issue visible.
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