I don't know why this was happening, but in /var/log/syslog I found some systemd-sleep logs. Haven't seen this in other ubuntu-server vms, but maybe helpful for someone else.
Fixed with this for now.
sudo systemctl mask sleep.target suspend.target hibernate.target hybrid-sleep.target
No...
Have an issue with a vm constantly getting put into suspended state after ~20 minutes. Have soft-rebooted, hard-rebooted, and re-built the vm with no fix. Have also tried a silly "keep alive" script in case the gpu-passthrough was expecting some terminal action before hibernating. Thinking...