I have entered on a new passport before , all I had to do was show my old passport . Then I went to Immigration when I got around to it and they transferred everything into my new passport , no real issues .
I flew in from Jakarta recently , didn't need to show vaccination cert when checking in at Jakarta and wasn't checked when I entered Thailand . Filled out an arrival card just in case but they didn't want it .
It has always been a requirement when entering visa exempt or on a tourist visa , in the past they haven't enforced it but maybe they are starting to now .