To answer your question i think we need to backup a bit and understand: how the tech works, why blooming occurs because of the tech, and how software is being used to eliminate the majority of it.
How the tech works: It is actually quite complex, and a radical change from other LCD techs in the past. If you watch the iFixit breakdown, you can see the backlight on its own now looks like a monochromic low resolution version of the image you see on the screen. This occurs because the LEDs alone are given enough resolution to be seen(~2500 zones worth to be precise). You might think that this level of control has always been available; it has not, and is a major accomplishment, even this late in the LCD screen’s lifespan.
Why Blooming Occurs because of the tech: Blooming is a cause of “light bleed” or observable light being somewhere it should not be. In an OLED screen: light is created at source for every sub-pixel. In an LCD screen: light is created by a backlight and pushed through color changing sub-pixels. The main problem with OLED is amount of filter that is required to create the image(if your unfamiliar with the current tech, White light is used with a filter for each sub-pixel: so ~70% of produced light is filtered to produce the required level of brightness for every color; this is the limiting factor in brightness of most OLED screens). With LCD because your light and image are created in parallel, the area in between allows for bleeding or blooming to occur. With ~2500 zones the new XDR screen can reach impossible blacks, but this also means any light created on these blacks are held to the same impossible starting point(LCDs always have starting point in it’s contrast ratio). So, there will always be blooming of some degree in LCD displays. That said, the human eye can only see so much contrast, and in most situations the new XDR screen on the iPad Pro shouldn’t really experience it(extreme low-light, or cameras with better than human abilities).
Software: this is the biggest issue with LCD tech. Because LCD doesn’t just create the image like OLED, it requires a bit more “hands on” work from the programming side of things(Think: Contrast Starting point, color interactions, new max brightness levels, reflections, etc). Essentially every color palette has to be re-ranged, and even certain textures have to be completely recreated. Most of the blooming your seeing is software related. As LCD tech matures the software gets more and more in tune with the display tech’s limitations, as this tech is fairly new; expect the majority of what your seeing to be solved.
What can never be solved: “The Halo Effect“ If you have never used an apple Micro-LED screen before: this effect can be a bit jarring, but the human eye ignores it fairly quickly… essentially, apple uses a 4 LED zone for its backlight. The LEDs are offset a bit in the zone so the LEDs all fit into each other creating a higher concentration of overall LEDs and less dark area in the zone, but this comes at a cost, as the edge of the screen has ~50% as many LEDs as the next available row… this creates the precipitation of a slightly darker edge than rest of the display or a “halo” of darkness around the edge. Honestly, this is a small price to pay for almost perfect contrast in darker areas and elimination of most blooming.
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