I have matte glass screen protectors on my Mini 6 and Air 4 in Zugu cases, no lifting. Have had screen protectors on both for the several months the iPads have been in the cases.
I like the lack of glare, the reduced fingerprints, and the less slippery feel when using the Apple Pencil. I don’t consider screen protectors silly at all. I had one break when an iPad fell face first on a hard floor and I had a plastic one get a divot in it when my iPad fell against the sharp corner of a metal camera display stand. I expect the screen would have suffered a nasty scratch or possibly even broken.
I use my Mini 6 outside when I check my trail cameras. The case alone would not protect the screen from scratches while I’m using the iPad in that outdoor environment.