/etc/timezone is intentionally no longer used any more. See the changelog for https://tracker.debian.org/pkg/tzdata
I recommend removing that file and then running sudo timedatectl set-timezone Europe/Prague You can run timedatectl list-timezones to find out the name of other timezones if that's not the correct timezone for you. I believe the actual bug here is https://bugs.debian.org/1119919 So that's why I suggested Prague since Bratislava is a symlink to Prague ls -lah /usr/share/zoneinfo/Europe/ Please let us know if this fixes your issue. Thank you, Jeremy Bícha
