When I saw Sunset in late March, the last note of With One Look (in both acts) was definitely not pre-recorded BUT it was also not belted. I had become so used to hearing Close belt that final note (albeit with a modified vowel) and had heard her do it that way as recently as a few years ago at the Hollywood Bowl. So I was very surprised that she used her head voice on the final note this time around.
Has Close been using her head voice for that section more often than not during this run? Maybe she has been struggling with that final note and the solution has been for her to mime it.