Bug#993070: Missing privilege separation directory: /run/sshd

Package: openssh-server
Version: 1:8.4p1-5

When disabling tunneled clear passwords, by setting
'PasswordAuthentication no' in /etc/ssh/sshd_config, it is no longer
possible to login, as the ssh server fails with the following message:

Missing privilege separation directory: /run/sshd

Manually creating the directory fixes the issue, but only until the
next boot. I have tried updating the RuntimeDirectory to /run/sshd in
/lib/systemd/system/ssh.service but that did not help.

I am running Debian Bullseye with a 5.10.0-8-arm64 kernel.

This issue might be related to
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=864190 but that one
is old and claims to be fixed.