Ours is a 2020 4.0 purchased last May. It’s not really making any noise I wouldn’t expect. We have what I think would be normal motor and gear whirring that varies with speed, but is not loud or bothersome. In the first month we had it there was a sound like a piece of sheet metal rubbing on a rotating part, but it went away on its own before I could get it back to dealer.

Okay, the sounds coming from our cart are very different from that. The noise from our cart is a very high pitched, pulsating whining sound with a grinding noise in the background. The only time the cart runs silently is when it is in reverse - except for the backup alarm, of course. After test driving several new carts of the same model at dealerships, we expected silent operation while driving forward, as well, especially at very low speeds on flat streets.
So there’s really no reason for us to compare the carts, though I appreciate the offer. Thanks.

Obviously they are not mechanics...They are just sales people.
It would be easy to find the noise if they were really "mechanics".

I suspect they thought the noise was coming from the transaxle since they installed "an additive". Differential gearsets are cut and honed to mitigate gear whine. No additive will help a poor gearset...You would need a transaxle gearset replacement. A differential whine is not really a problem except the noise is annoying and you paid EZGO for a "silent" transaxle at purchase.

They are obviously just trying to get you to go away. What you fail to understand is that the quiet transaxles are the ones with problems...not the noisy ones. Tell them you want your problem-free noisy transaxle replaced with a quiet problematic one :)