How does this apply to the NHK trophy though? N/N *lost* the FD TES to both the French and the Danish teams but beat them both in the PCS. They still placed behind F-B/S in the FD, and both teams scored a FD personal best by quite a margin, so it wasn’t like the judges were trying to dump the Danes.
It catches my eye when the PCS order changes between the SD and FD, which happened here with N/N and F-B/S. Also, it catches my eyes when a team beats another team in the PCS for the first time head-to-head, which also happened here with these two couples. I think in this case, it may be just that this panel particularly enjoyed their FD, like you listed as a reason for PCS fluctuations.