After installing the current September version of Home Assistant OS (the Beta version as of today), if you have Home Assistant OS installed in a Proxmox VM and the CPU allocation isn’t defined, Home Assistant OS won’t start after installation.
If you’d like to take a look, it’s explained here.
Wow, for anyone who stumbles on this.
Nothing crashes and the issue will likely be rolled back to give folk time to change their settings ahead of time. The issue being that a dependency update requires certain abilities from the CPU and a lot of VMs do not have their CPU type correctly set. It’s a simple fix, no hyperbole required.