I think I have the same noise in my Jan 2021 built MYP. Started after several months in August 2021. First from one side. Then on both sides. It’s a metallic click sound that at first I thought I got something loose under the rear seats. But then we heard it from the outside too. It only happened under rapid acceleration and deceleration (so there is a toggled shift of something in suspension in both directions. Lately it happens when going over large bumps like entering a driveway curb. So vertical acceleration too.
When I finally took it to Tesla service in Nov 2021, they changed all rear brakes, rotors, pads, lubed all they could and retorqued every bolt. It did not solve problem.
Next day I was accepting that the whole car will have to be taken apart but got a message from service that they consulted with Tesla engineering and apparently it’s a known issue that Tesla knows and is working on a fix for. Message says “the noise is coming from where the subframe bolts up in the rear of the vehicle.” But is not a safety issue (wheels won’t come off).
I followed up just a few weeks ago in mid-Feb 2022 and there is still no fix for it.
I’m thankful Tesla was very forthcoming with the cause of the noise.
The noise to the best of my interpretation sounds like two large steel balls collide. It’s always a single click per each side. I got used to it by now but worries me a bit it started happening lately with vertical accelerations when going over large bumps.
Anyone else has this or knows more? Diagrams of where this is actually happening and potentially how?