The system doesn't power down

[Emmanuel DA MOTA]

step to reproduce is very simple

$poweroff

the desktop quits, the screen goes black but the computer never shutdown

last lines from journalctl are

juin 23 16:20:10 pc1 systemd[1]: Reached target Shutdown.
juin 23 16:20:10 pc1 systemd[1]: Reached target Final Step.
juin 23 16:20:10 pc1 systemd[1]: systemd-poweroff.service: Succeeded.
juin 23 16:20:10 pc1 systemd[1]: Finished Power-Off.
juin 23 16:20:10 pc1 systemd[1]: Reached target Power-Off.
juin 23 16:20:10 pc1 systemd[1]: Shutting down.
juin 23 16:20:10 pc1 systemd-shutdown[1]: Syncing filesystems and block devices.
juin 23 16:20:10 pc1 systemd-shutdown[1]: Sending SIGTERM to remaining processes...
juin 23 16:20:10 pc1 systemd-journald[407]: Journal stopped

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: systemd 245.4-4ubuntu3.1
ProcVersionSignature: Ubuntu 5.4.0-37.41-generic 5.4.41
Uname: Linux 5.4.0-37-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.11-0ubuntu27.3
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Tue Jun 23 17:37:52 2020
InstallationDate: Installed on 2014-06-03 (2211 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417)
MachineType: Gigabyte Technology Co., Ltd. H61M-D2-B3
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.4.0-37-generic root=UUID=6081a4ec-8716-452d-98c2-c59ace5a96b7 ro quiet splash vt.handoff=7
SourcePackage: systemd
UpgradeStatus: Upgraded to focal on 2020-05-21 (32 days ago)
dmi.bios.date: 03/27/2012
dmi.bios.vendor: Award Software International, Inc.
dmi.bios.version: F10
dmi.board.name: H61M-D2-B3
dmi.board.vendor: Gigabyte Technology Co., Ltd.
dmi.board.version: x.x
dmi.chassis.type: 3
dmi.chassis.vendor: Gigabyte Technology Co., Ltd.
dmi.modalias: dmi:bvnAwardSoftwareInternational,Inc.:bvrF10:bd03/27/2012:svnGigabyteTechnologyCo.,Ltd.:pnH61M-D2-B3:pvr:rvnGigabyteTechnologyCo.,Ltd.:rnH61M-D2-B3:rvrx.x:cvnGigabyteTechnologyCo.,Ltd.:ct3:cvr:
dmi.product.name: H61M-D2-B3
dmi.sys.vendor: Gigabyte Technology Co., Ltd.

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This change was made by a bot.