I can confirm that tapping into neutral eliminates the high pitched noise immediately and 100% of the time. I showed the lead tech at Tyson’s Porsche in DC during a drive along to diagnose and he said “this is behaving as expected”. This was a super disappointing response and I agree with others...
I showed my advisor the TSB (since I have had the same brake pedal feel/travel issue) a few weeks ago and we did a brake flush. My car had about 18k miles on it and is about two years old. I'd say that the feel is more consistent now. I don't know that any software was updated.
The other...