I don't think it's due to the slimmer bezels. My first-gen 12.9 Pro had the same issue and I got a replacement at an Apple store. The replacement (my current device) has been fine from day one. The screen just feels more solid all around. I'm thinking about picking up a 10.5 Pro this weekend but all these posts make me a little nervous.
I wouldn't let the fear of a bad unit/panel overwhelm me out of giving it a try. It's always been a lottery, I think the odds are just unfavorable considering I had three in a row, with same problem same area
But I also wouldn't go far down the rabbit hole to get a decent one, unless you want to or you're coming from an ancient iPad and are compelled to upgrade this cycle
You can only get a good unit if you try! First shot nTB I nailed it, I still maintain I may have the best panel of anyone on this board who has posted theirs, and the MBPs are supposedly an absolute frustrating nightmare of swaps to deal with.
Same with my Pro 9,7 but I had a few bum units before (I think 2 or 3)
7+ I'm a little nit picky of but still have same first unit I tried, though there was no stock for months anyways so if it was horrendous I woulda been SOL.
I had one crappy 7, and one that was comically bad before going back to Plus (tried 4.7" temporarily, not my size period, so the crappy displays helped push me over the edge but been on 5.5" since 6+ now)
Of all products, I think iPads are the one that are least PITA. Tons of stock, relatively no IRL hype, no potential ties to payment plans/messy terms, etc. (though I pay full retail for my unlocked iPhones)
Id think laptop swaps are the biggest headache, or bulky 27" iMacs to haul around
Thats A LOT of money to put on one's credit card multiple times, and to not get some raised eyebrows on burning through expensive inventory