I think you just have to accept the fact that there is no such thing as a "perfect" display. When you're actually using the screen for work, you typically don't notice issues like backlight bleed, uneven uniformity etc. 5 returns is insane and I'm surprised they let you do that. Your OCD lost them tons of money, time, and effort.The ASD is my biggest disappointment so far – I love everything about the design and built quality, but can't find a uniform enough screen (which is, well, the most important part of a monitor).
I went through 5 displays in a month and all are bad. Some had a pinkish tint on the sides that was too visible to be ignored. Others had a pretty bad dirty screen effect. All are worse than my 5k iMac from 2019.
Considering the price, I can't understand how Apple can ship monitors with such poor-quality panels. I even talked to Apple on the phone, and they just suggested I try ordering again and hopefully get a better panel.
The display is not perfect, but it is by far and away the best option for Mac users who require an external monitor.