Put the thin white sheet that comes with the Mac in-between the keyboard and screen. If one doesn't have that anymore, a very thin soft cloth or piece of paper will work. Just make sure to mark the keyboard down side of the sheet or piece of paper so that you don't get finger oil smudges on the screen.
I have it on an M4 as well. I do find it to be quite fingerprinty. I know Apple says only to use their cloth to clean it, but once when I went into the store, one of the techs told me that the basic alcohol wipe would be fine.
I am doing the same thing: thin microfiber cloth on the keyboard whenever I close the lid
Nothing - I've never experienced them. But my MacBook rarely leaves the house. I wonder if those who suffer from keyboard imprints tend to carry it in a bag with other items, potentially applying pressure to the enclosure.
Clean the keyboard every now and then, the imprints mostly come from the oils from fingers. Also avoid putting into tight places, or over stuffed bags.
