By default systemd includes journald, rather controversial (and mentioned in a comment on this thread) picked binary logging (harder for humans) and much less robust in the face of a small corruption, and ignored encryption. I believe it doesn't support encryption (by default). This replaces more robust solutions (by default) like syslog-ng and rsyslog that have long histories of battle tested real world usage.
resolved replaces the local DNS resolvers, and at least for awhile ignored DNSSEC. This is particularly bothersome since it is such a security sensitive daemon. Sure you can disable it and pick unbound, but it's not default.
timesyncd is a time daemon, replacing NTP, another security sensitive app. Not that NTP is a paragon of security, but various projects have arisen to improve things.
networkd is a replacement for DHCP and similar for IPv6. Again not nearly as nice or secure as existing solutions.
So basically decades of developer work, security audits, and competition among network services had been ditched and is now part of systemd and a typically cavalier attitude towards security.
There are good parts of systemd, it filled a need. But this swallowing of security sensitive network services really bugs me. Being able to be compromised so early in the process and the tight integration going against the idea the unix philosophy of using minimalist modular software. Normally I'd run unbound as a non-root user with access to read few directories, and write to even fewer, DNSSEC enabled, and logging via syslog (human readable). By default on an ubuntu 20.04 (and 18.04 before that) I'd have issues with dns failures... till I replaced the systemd resolver. I'd mention it to other admins and they would shrug and mention that systemd sucks.