tzdata-2024a-3ubuntu1.1の/usr/share/doc/tzdata/changelog.Debian.gzにありました (2024a-0ubuntu0.22.34.1にはありませんでした):
> tzdata (2023c-8) unstable; urgency=medium
> :
> * Ship only timezones in tzdata that follow the current rules of geographical region (continent or ocean) and city name. Move all legacy timezone symlinks (that are upgraded during package update) to tzdata-legacy. This includes dropping the special handling for US/* timezones. (Closes: #1040997)
なるほどなあ
https://bugs-devel.debian.org/cgi-bin/bugreport.cgi?bug=1040997
bugs-devel.debian.org#1040997 - tzdata: remove country name symlinks from top-level directory for better organization - Debian Bug report logs