Took delivery of MYLR in mid Aug 2021. It's a constant hum when car is activated and in use. NO fan, no AC, parked for hours, no climate control, temp here has been low 70s - it doesn't matter the hum is there. The hum is gone after 30-60 minutes after being locked and parked.
That said, I took it to get supercharged and hum and noise was just unbearable. It sounded like the same noise but just louder.
I am sorry about that, and thank you for posting your testimonial! I haven't tried supercharging yet, but I'll try.
Have you contacted your nearest Tesla Service Center about it? Please, do it and insist on it. Tell them many other people are complaining about this issue.
Please, keep us posted.