Unfortunately I have also been affected now, after 11 months, but with a bright spot in the very right lower corner. Not visible in dark mode, also in most app that have a darker banner/area when using in landscape (like Safari tabs), but still slightly annoying. Luckily I was still in warranty for 1 month, so I get a free replacement by Gravis (Germany). I don't mind a brand-new looking unit with 0 battery cycles. So going to use that until around next summer and then sell it.
I really, really love the 10,5" Pro! In my eyes it is the best iPad device Apple ever made (for its time). Balanced size and portability, A10X, 4GB RAM, a still great camera with OIS + flash, badass speakers, 120Hz and I prefer the design + home button over the newer models. Bezels are thin enough, especially on the sides, definitely anything than looking "outdated". However, this bright spot just spoils the perfection, which is a huge shame. Couldn't they make all Pro and Air models just a little thicker (like +0.5mm), to make them more robust, cooling friendly while getting a smaller camera bump on the same time?