Thanks to Mackensen on New York Yimby forums for finding a close up cam of the construction of the PAC.
Since December 15, 2021 there has been additional construction taking place at the roof level. This appears to be some sort of paneling overlain on top of the concrete roof.
The zoomed in cam available at the linked URL shows this. To change the date to view how construction has progressed, edit the YYYY/MM/DD date portion of the URL.
Progress:
December 15, 2021
December 17, 2021
January 1, 2022
January 11, 2022
February 11, 2022
More equipment continues to be moved to the roof. No sign of more marble cladding or the beginning of black granite installation at the base.