Regarding more people declining the second shot than the first shot, my best guess would be that people took the first shot, and either they themselves or one of their acquaintances had an extremely bad side effect, either actual or perceived, so they decided not to take the second shot. I know one person who followed this reasoning. Her husband fell ill after his vaccination with unclear causes, and she attributed it to the vaccine. She finally did decide to get her second shot and booster recently.
Another possibility could be that some financial incentives incentivized the first shot but not the second shot.
Regarding more people declining the second shot than the first shot, my best guess would be that people took the first shot, and either they themselves or one of their acquaintances had an extremely bad side effect, either actual or perceived, so they decided not to take the second shot. I know one person who followed this reasoning. Her husband fell ill after his vaccination with unclear causes, and she attributed it to the vaccine. She finally did decide to get her second shot and booster recently.
Another possibility could be that some financial incentives incentivized the first shot but not the second shot.