This gen's release of FromSoft's Armored Core 6 sold over 700k copies across PC, PS5, and PS4 in JAPAN ALONE. It is arguable whether Final Fantasy 16 was able to hit that number between its roughly 450k physical sales, and unknown digital sales on PS5 in that region. The trends worldwide all show it clearly behind Final Fantasy 15, and 7 Remake. Rebirth was tracking behind 16 in almost every market as well. These are clearly sales disappointments, as they show a declining trend for these tentpole releases at a time of increased costs/budgets, and developments times compared to predecessors that performed better.
Rebirth performing notably worse than Remake doesn't scream good PR, nor make a case for even more resources being poured into its follow-up (third game won't be made on the cheap though --no worries). Other market trends show PC/Steam is making a serious dent in Japan, and worldwide, and continuing to grow. Nintendo is the clear market leader in Japan right now for home consoles, lest they goof up with their next hardware. Sony's on the road to pricing themselves out of that market (Japan), and the President of SE clearly believes a multi-platform approach is necessary for the company now, in light of these trends, and has signaled exclusivity as a problem/missed opportunity for these big games.
There is many other things we can discuss specific to these two tentpole titles (16/Rebirth), but clearly these are initial sales disappointments that have missed early projections, and strategies are changing/being reanalyzed. That much is clear.
That being said, both these games are still considered success stories, and they will continue to get pushed years down the line with their inevitable re-releases.