My M1 MacBook Pro makes that sound as well, and I asked for a replacement, but the new one doesn't. There are 12 M1 MacBook Pros in my office, I tested them all, and 3 (or 4, I don't remember) of them have this sound. I guess this problem does not happen to all, but it does happen. If there is an Apple Store near you, you should go and ask Genius Bar, and ask if they can fix it. Anyway, if it doesn't bother you, you don't need to worry about it.
By the way, I found another problem with mine, as the picture showed, there is a gap between the rubber band and the keyboard kit, I only noticed this problem on 6 of 12 Macs in my office, and I checked out my friend's 16-inch model, his does, so is this a common problem?
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