I have the same issue. I find solution here :
https://forum.proxmox.com/threads/proxmox-7-lxc-ssh-root-login-not-working.93752/page-2
systemctl mask ssh.socket
systemctl mask sshd.socket
systemctl disable sshd
systemctl enable ssh
Now process use /etc/ssh/sshd_config file and all work after...
