Man pages matching name system.conf.d in section 5:

system.conf.d.5.de	debian 10 / manpages-de
system.conf.d.5.en	debian 10 / systemd
system.conf.d.5.de	debian 11 / manpages-de
system.conf.d.5.en	debian 11 / systemd
system.conf.d.5.de	debian 12 / manpages-de
system.conf.d.5.en	debian 12 / systemd