app-crypt/tpm2-tss installs its own sysusers.d config file for its user, even though these are already provided by the corresponding acct-*/tss packages. This leads to systemd-sysusers throwing warnings. $ equery f tpm2-tss | grep sysusers /usr/lib/sysusers.d /usr/lib/sysusers.d/tpm2-tss.conf
Fixed in https://github.com/gentoo/gentoo/commit/ca44589bcf74c1a331ed8948bf2357bcb4d6870a