Applied the amFilm matte glass screen protector to my iPad Mini 6. I really didn't want to cover that beautiful high-contrast low-reflectivity screen, but I use the mini primarily in the cockpit of my two-seat airplane. Since that's a pretty cozy space, the iPad is mounted vertically off to the side.
Unfortunately, Apple rotated the native direction of the display by 90-degrees compared to the previous iPad Mini 4 that I had. The old iPad was "native" in portrait, so also the natural compatibility with polarized sunglasses. Now the Mini 6 is "native" in landscape orientation, and the display dims a bit in portrait when wearing polarized sunglasses. It turns out putting a matte screen protector on scatters the polarization, so the display is just as bright in either orientation when wearing polarized sunglasses. Yay.
I suspect this change is the same one that made the infamous "jelly scrolling" more obvious. My old iPad exhibited that effect in landscape mode. The new one does it in portrait mode. Doesn't bother me... all displays have their quirks.
All that said, if it weren't for my specific requirement, I wouldn't use the screen protector. The Mini 6 has one of the best glass coatings I've seen yet: low reflectivity, oleophobic, and high contrast. The matte screen protector definitely ruins a lot of that.