Chiming in with my experience with this.
Bought the Pro 10.5 on release day. Display went nuts last March (looked like a bad display cable - multi-colored lines/static across the screen, flashing, etc) and was replaced under warranty.
Replacement unit developed a bright spot directly above the Home Button in July - I assumed it was just a freak thing and didn't do any research at the time, and after a bit of a runaround, it was also replaced for free, even though it was outside the 90-day replacement warranty. Kudos to Apple on how they finally resolved that one.
The third unit started showing a bright spot in exactly the same spot a few days ago - not as bright as the last one, but I assume it will get worse. Did a support chat, took it in to the Genius Bar today, and, while the Genius admitted she could see the bright spot, it passed all diagnostics, and I was offered the $449 repair or trade-in at $318. They're not getting enough complaints to make the issue "official", so we're at an impasse.
I'm more than a little disappointed in Apple. There was a time when they would have made this right, but those days have apparently passed. I've had three 10.5 Pros, and not one has made it to a year without developing a display issue. I love the size and form factor, I'm not bowled over by the 2018 Pros (especially the price), and nothing else ticks all the boxes for me (not even the new Air, which lacks the speakers of the Pro - I use mine to listen to podcasts all the time, and need the extra volume).
There are basically no good options here - it's a minor issue that will probably get worse over time, Apple is disinclined to do anything about it, I don't really want to spend $300+ (refurb minus trade-in) to get another unit that may develop the same issue, and I don't like the cost of upgrading to the 2018 11".