Nvidia driver packages prevent suspend due to leftover Systemd units

When the nvidia driver packages are uninstalled, they leave some symlinks that prevent suspend.

I whink that, when attempting to suspend, the error is logged as this (edited):

    ModemManager[3287]: <warn> [sleep-monitor] inhibit failed: GDBus.Error:org.freedesktop.DBus.Error.NoReply: Message recipient disconnected from message bus without replying
    upowerd[5771]: Could not acquire inhibitor lock: GDBus.Error:org.freedesktop.DBus.Error.NoReply: Message recipient disconnected from message bus without replying
    dbus-daemon[2888]: [system] Activating via systemd: service name='org.freedesktop.login1' unit='dbus-org.freedesktop.login1.service' requested by ':1.53' (uid=1000 pid=8227 comm="/usr/lib/x86_64-linux-gnu/indicator-session/indica" label="unconfined")
    systemd[1]: systemd-logind.service: Main process exited, code=exited, status=1/FAILURE
    systemd[1]: systemd-logind.service: Failed with result 'exit-code'.
    systemd[1]: systemd-logind.service: Scheduled restart job, restart counter is at 7.
    systemd[1]: Stopped Login Service.
    systemd[1]: Condition check resulted in Load Kernel Module drm being skipped.
    systemd[1]: Starting Login Service...

I've deleted the problematic symlinks while trying to solving the problem, however, they should be these:

    /etc/systemd/system/systemd-suspend-service.requires/nvidia-suspend.service
    /etc/systemd/system/systemd-suspend-service.requires/nvidia-resume.service
    /etc/systemd/system/systemd-hibernate-service.requires/nvidia-suspend.service
    /etc/systemd/system/systemd-hibernate-service.requires/nvidia-resume.service

I've briefly checked before removing them; at least a couple of them were masked, but they were still causing the problem.

I don't see any reason why they should hang around the systemd configuration once the packages are purged. Additionally, this is a problem that is not easy to diagnose.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: nvidia-driver-470 (not installed)
ProcVersionSignature: Ubuntu 5.11.0-27.29~20.04.1-generic 5.11.22
Uname: Linux 5.11.0-27-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu27.18
Architecture: amd64
CasperMD5CheckResult: skip
CasperVersion: 1.445.1
CurrentDesktop: MATE
Date: Mon Aug 30 21:10:52 2021
LiveMediaBuild: Ubuntu-MATE 20.04.3 LTS "Focal Fossa" - Release amd64 (20210819.1)
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=C.UTF-8
 SHELL=/bin/bash
SourcePackage: nvidia-graphics-drivers-470
UpgradeStatus: No upgrade log present (probably fresh install)