I believe this A320 did not have pax vests, since it does not overfly large stretches of water. The vests seen probably came from the rescue boats.
This seems possible. If you look carefully you can see large numbers of seat-bottom cushions floating near the wing, in the photos taken after most of the passengers had gotten away. Perhaps the passengers took these at first and then switched to the life vests when they were tossed to them from the ferry crews.