Unable to install virtualbox-dkms through `sudo apt install..`

[H]

While installing virtualbox, apt failed during virtualbox-dkms configure process :

  ...
  Paramétrage de virtualbox-dkms (6.1.38-dfsg-3~ubuntu1.20.04.1) ...
  Removing old virtualbox-6.1.38 DKMS files...
  Error! You must be root to use this command.
  ...

After further investigations, I found out what exactly was blocking :

  % sudo dkms autoinstall
  Error! You must be root to use this command.
  % sudo whoami
  root
  % sudo id
  uid=0(root) gid=0(root) groupes=0(root)

First, I had to launch a shell, then I could run dkms...

  % sudo -s
  # dkms autoinstall
  vboxdrv.ko:
  Running module version sanity check.
  Error! Module version 6.1.38_Ubuntu for vboxdrv.ko
  is not newer than what is already found in kernel 5.15.0-60-generic (6.1.40).
  You may override by specifying --force.
  ---snip---

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: virtualbox-dkms 6.1.38-dfsg-3~ubuntu1.20.04.1
ProcVersionSignature: Ubuntu 5.15.0-60.66~20.04.1-generic 5.15.78
Uname: Linux 5.15.0-60-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.25
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: GNOME
Date: Mon Mar 20 10:59:44 2023
InstallationDate: Installed on 2023-02-28 (20 days ago)
InstallationMedia: Ubuntu-Server 20.04.1 LTS "Focal Fossa" - Release amd64 (20200731)
SourcePackage: virtualbox
UpgradeStatus: No upgrade log present (probably fresh install)