Because it hasn't even been ported away from KDELibs4Support! This is already known to various people, but I'm making a Bugzilla ticket for it so we can track it among all other Qt6 issues in a central location.
A possibly relevant merge request was started @ https://invent.kde.org/plasma/plasma-desktop/-/merge_requests/1762
Git commit 8a4788e9daa4841c1457153be1a2d0712bdf575a by David Redondo. Committed on 07/11/2023 at 17:07. Pushed by davidre into branch 'master'. kcms/dateandtime: Port the date and time kcm to KF6 Aside from the usual kf6/kcm porting and using KSvg instead of plasma-framework the meat is in migrating away from the KDE4-era KTimeZone classes QTimeZone can be used for most of it, the only thing missing are the translations for continents and cities (Europe/Warsaw -> Europa/Warschau). We can use ICU to retrieve a city name. The digitalclock applet which also deals in timezones there we maintain a list of translated contintent names. Its translation catalog is used to obtain these here until a better solution for this comes to light. M +8 -0 CMakeLists.txt M +6 -8 kcms/dateandtime/CMakeLists.txt M +20 -14 kcms/dateandtime/dtime.cpp M +4 -2 kcms/dateandtime/dtime.h M +63 -54 kcms/dateandtime/k4timezonewidget.cpp M +3 -12 kcms/dateandtime/k4timezonewidget.h M +16 -34 kcms/dateandtime/main.cpp M +1 -1 kcms/dateandtime/main.h https://invent.kde.org/plasma/plasma-desktop/-/commit/8a4788e9daa4841c1457153be1a2d0712bdf575a