Where are you encountering buzzing feedback? I don't think I've experienced that in any Mac laptop I've used in the past 20 years. There's the haptic feedback from clicking but that's singular, distinct, and non-repeating.
Could be the electrical nature of the case? When I used a Macbook for work, if it was plugged in (original charger and cable and all) then dragging my finger over the chassi or trackpad could be described as a "haptic buzz", it felt like there were ridges on it, like corrugated cardboard. When unplugged and on battery, it would feel smooth.
Yep, that's probably because the power adapter wasn't grounded.
Here in Europe, at least in 2013, the adapter had two ways of plugging into an outlet: a cable and a plug that could be clipped on. The plug only had two prongs, while the cable had a ground connector. I'd get the "buzz" if the adapter wasn't grounded.
This also happens with my HP laptop if I plug it into an ungrounded usb-c adapter, so I'd expect the same thing to happen to iPads.
