quick google search shows it might have something to do with disabling screen locker and power savings for inside vms. maybe its related to whonix since its here on github. https://github.com/Whonix/power-savings-disable-in-vms/blob/master/etc/profile.d/20_power_savings_disable_in_vms.sh
I guess unless your vms are blacking out I wouldn't worry about it, probably something that was being tested.