Oh God- don't even get me started. Having the same issues as you did- iPads 8 and 9 are coming tomorrow.
It all started on Black Friday when I purchased three from Target (I am well experienced with Apple's lack of quality control with screens, so yes, I knew to purchase more than one at a time with the odds of getting an unacceptable unit).
Anyway, one had a bright white spot in the screen, the other had a black particle visible on light backgrounds- I returned those two and I kept the third thinking it was fine, but after a few days I noticed it had a small area that is very dark along the left edge. I wouldn't have had a problem with it had it been the entire edge and uniformly darker, but while scrolling text on a web page or in iBooks, it is very noticeable and annoying as the words go though light and dark areas.
I purchased two refurbs from Apple - on the first iPad, half of the screen looked gray and dingy as if it was dirty (no other way to describe it), the other iPad- half of the screen was visibly pinkish on white webpages. Sent those two back for a refund.
Ordered two more from Walmart - one had a dead pixel, the other was pretty good on white pages - one corner is visibly darker but bearable .... but it has awful spots of backlight bleed with black backgrounds.
So, I ordered two more from Best Buy this time, and this is my last try. They're arriving tomorrow.
I honestly don't think I am being outrageous when I expect a decent screen on a Pro device. My iPhone 5S has a great screen and that only took me two tries (first device had a dead pixel and the Apple Store genius saw it right there when I purchased it and opened it in front of him, so he took it back and gave me another - that one had bad spotlighting at the top edge which he also saw, gave me a third and it's perfect).
I am an artist and will be using this screen with stark white and black backgrounds quite often. I need uniformity. Call me whatever you wish, I don't care. It's my money, and I am not an idiot. I have had bad luck in the past with Apple's screens, but this is the worst so far. I have no other complaints with the devices - and I would happily accept a unit with a scratch or a scuff on the aluminum to get an acceptable screen. And no, I am not interested whatsoever in devices from other companies. I love Apple products, their software, and their ecosystem. I'm not leaving- I just hope these screen issues become a thing of the past whenever Apple switches to another manufacturing process or type of screen.
EDIT: By the way- I only ordered one Apple Pencil and of course it was perfect on the first try. I love my Apple Pencil!