Has your drive unit ever been replaced (particularly after 2015)? If not, then the "milling" is a very common issue on older drive units. If it has been replaced, then there's a high likelihood that your coolant seal has started to go bad, and has washed the grease out of the rotor bearings. If it is indeed coolant leaking internally, then the drive unit is a ticking time bomb, which could develop and isolation fault, or even worse, short out the inverter electronics...
My advice, get in touch with Tesla, and see if they will good-will the drive unit (make sure to bring up that you brought the car in before with a similar complaint while it was still within the warranty period). In all likelihood, Tesla most likely won't be willing to replace your drive unit at no cost, but a few have been lucky, so maybe you will be too...
If Tesla says no, then you can try bringing the car in to a 3rd party shop (like the one where I work) to be looked at. We rebuild these Large Drive Units all the time (literally multiples every week), so we are very experienced and have learned the nuances and problems that are common to encounter. I can definitely tell you that waiting until the Drive Unit fails is a bad plan, and it gets much more expensive to repair if the inverter or something else gets permanently damaged...
I highly recommend that at a bare minimum, you should do a speed sensor check to see if there is coolant getting into the motor, as that will give you a clue as to what is causing you issue, and whether or not you should continue driving the car.