universe/archlinux-keyring
I noticed, that package universe/archlinux-keyring owns those files
pacman -Ql archlinux-keyring
archlinux-keyring /archlinux-keyring-wkd-sync.service
archlinux-keyring /archlinux-keyring-wkd-sync.timer
archlinux-keyring /timers.target.wants/
archlinux-keyring /timers.target.wants/archlinux-keyring-wkd-sync.timer
which are placed in / directory for no reason;
for comparison, Arch Linux version of package has those files in
usr/lib/systemd/system/archlinux-keyring-wkd-sync.service
usr/lib/systemd/system/archlinux-keyring-wkd-sync.timer
usr/lib/systemd/system/timers.target.wants/
usr/lib/systemd/system/timers.target.wants/archlinux-keyring-wkd-sync.timer
(absence of trailing slash on Arch's site is normal, hence pacman install all packages in RootDir from /etc/pacman.conf)