Thoughts on Keyboard cover use from my experience.
I have a Mosiso keyboard cover on my mid 2013 13" MBA. After years, it has left marks on the screen.They are really only noticeable with a black screen -and- tipped at a strong angle. Obviously, taller keys and a different animal. My marks might be from the cover getting dirty as I use it on my office coffee service route to inventory each break room and my hands get dirty.
Is there anyway to find a spec for the OEM distance of keys to screen and the +/- tolerance? That info and keyboard cover's thickness spec would give a theoretical insight if a KB cover should or should not contact the screen. The only way that I could think to real world test a KB cover, is to apply a thin film on several keys, then open close the lid numerous times and maybe leave it sitting closed overnight. Then, with black screen, check screen at an angle in the light. But, now thinking of my years of 'dirty hands' use on my old MBA and the not too bad marks on my old school screen, I think for my new M2 MBA, I'll again use a cover, but 1) I'll try to clean my hands more often and 2) surely clean the KB cover occasionally! ;o) 3) maybe even replace it after it gets looking aged.