I have seen plenty of laptops which come from the supplier with a sheet of material between the keyboard and the screen but I have (and others around me) binned them when removing all packing material from the device. I have never come across anyone retaining this.
Certainly amongst older laptops the clearance between the keyboard and the screen was very close and it was common to have the shape of the keyboard imprinted on the keyboard.
All current devices I have seen tend to have a modern low profile keyboard (which doesnt stick up above the palm rest) and the modern screens seem to have much better screen protection as well.
So I don't worry about it!
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