As of today, my second 2017 iPad Pro has also developed backlight bleed on the bottom edge of the screen. (I have a charging stand, and use my iPad Pro almost like a desktop computer, so there is a definite “bottom” to it.) I got my first iPad Pro replaced for the same reason after about 11 months. The replacement’s screen has been perfect for about nine months since then, but just started to exhibit the same problem today.
I wonder what is causing it. I hope it is not due to charging, pretty much exclusively, by the Smart Connector, because that’s how I have it set up. Anyhow, I am stuck with it now for a good, long time, because it is out of warranty and was very, very expensive. Hopefully I can train myself to un-see it.