Wondering if that noise is actually coming from the speakers. That ground strap would suggest so. I have exactly the same problem (high pitch at 2.8Khz) but with my TMS P90D 2016 pre lift. I have found the front ground strap under frunk but it's tightening doesnt do anything. As far as I can tell its grounded to the inverter side. It must be same generic problem with Teslas drive units I would say. TMS is probably better sound proofed than TM3 so its probably quiter but still I hear it and its annoying. Was considering soundproofing firewall/engine but when I looked at it its already well done by Tesla so no room to improve really there. Not sure what else can be done about it.