The reports of blooming on the Mini-LED seemed a little overblown (snort) to my eyes as the screen on the iPad Pro 12.9" looks fantastic to me, but your tastes may vary. That said, I'd love to see the iPad Mini get the screen tech upgrade treatment (Mini or OLED) as it has quickly become my favorite iPad for everyday use.
It's bad enough that it's an issue. I agree that in normal usage it's fine, but it is definitely obvious when in environments with darker lighting. What's curious though is that the new MacBook Pros don't have nearly as much blooming. Wonder if this was a refinement of the technology or just something inherent in laptop displays that prevents blooming. The 120hz on a MacBook also doesn't feel quite as buttery smooth as on an iPad Pro.