The en_US.UTF-8 locale gives you a 12 hour clock. Nothing new with that. As you indicated, you can change the behavior by assigning some other locale to LC_TIME. But you probably want C.UTF-8 rather than C to avoid the surprises you mentioned.
I see no bug here. Closing. If you need help to configure your system, please ask for support at e.g. <https://askubuntu.com>. If you find a bug, please report it as such, but try to be specific about the behavior you see vs. expected behavior. ** Changed in: glibc (Ubuntu) Status: New => Invalid -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1843366 Title: [eoan][2.30] locale woes, 12 hour clock and other issues To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/glibc/+bug/1843366/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
