Ah yeah, then the problem is you need to uncomment the worker_processes:
# nginx['worker_processes'] = 4
remove the comment hash, run reconfigure, and nginx will be fine. There are some posts on here about it already relating with LXC under proxmox: GitLab Webinterface not reachable after update to 15.1.0 - #2 by samansohani
So it seems when using LXC you need to uncomment this.
As for gitlab-runsvdir, it would have just saved you the reboot, after you rebooted, this service was restarted anyway.