Debian 13 got rid of default support for the ancient "US" time zone names like "US/Pacific", which were already obsoleted by geographic zone names back in the last millennium. At the time this caused a certain amount of blog and forum noise from people who insisted that using zone names like "US/Pacific" instead of the geographic zone names was perfectly fine and safe and why did these useful names need to go away?

Well, today British Columbia announced it will soon stop doing seasonal time changes. To everyone who has anything running there and who insisted on "US/Pacific" being perfectly fine, I say: good luck, have fun updating your systems, and this is precisely why you should have been using geographic zone names (in this case, "America/Vancouver") all along.