If a system's timezone is updated, rsyslog doesn't find out about it. Arguably, this only applies to travelling laptops, but rsyslog is the default Debian logger on this, which is why I think this is worthwhile to think about. Many other tools automatically adjust on timezone changes, whether that is through inotify on /etc/localtime, not caching the timezone in the first place, or some other mechanism provided by the OS. Please consider something similar for rsyslog.