I have super dry skin and I also feel that weird ac effect when lightly touching and moving along the surface of pretty much any aluminum mac device since they started making them aluminum.
And almost no other device I've ever used. My aluminum Framework does not do it. My wifes magnesium LG Gram does not do it.
I have felt it on other things but only extremely rarely. It's bizarre that whatever it is they're doing different, it's probably wrong, and they've kept doing it in every device for decades.
To describe the effect in more detail for anyone who doesn't already know: It's like the case is alternately grabbing and releasing your skin at 60hz.
It's a bit like chatter, ie the periodic friction you use to ring a wine glass by wetting the rim and then running your finger along it. It rings because the combination of the friction, the lack of friction from hydroplaning, and the rubbery give of your skin, makes your skin alternately grab and release 30,000 times a second. Only in this case you are only barely touching the case not pressing enough to make any friction or make a squeal noise. It's like static electric charge attraction. Just touching the case you feel nothing, but move your finger along the surface and you feel it vibrate your finger without any friction to explain it.
It's unsettling and displeasing, which are strange words to expect from an apple device at least when you are only talking about the design and not the tech stack or corporate behavior. It makes me think of cheap electronics from a country with no consumer safety regulations that will probably burn down every 3rd house they wind up in.
It's probably harmless, but then again a lot of things that are harmless in short infrequent doses turn out to have been harmful after you did it for 10 hours a day for 20 years.