error right after installation finishes, desktop environment with everything looking big after first boot

[Helena]

This seems to be related to installation with "Third party software" (see update.5 below).

(not a Linux expert here) I have tried installing both Ubuntu 20.10 and 21.10, and both showed me errors right after installation. For 20.10 the bug has supposedly already been reported, but this time it seems not (this report refers to Ubuntu 21.04).

After installing Ubuntu 21.04, with the optional third party drivers and using the "erase and install" option, two bugs appeared and the desktop looks weird.

The bugs are these:
1. "installed shim-signed package post-installation script subprocess returned error exit status 1"

2. "an error occurred while installing packages:
E: Sub-procecss /usr/bin/dpkg returned an error code (1)
the following packages are in a broken state:
[suspiciously blank space, something should be listed here]
this may be due [...]"

After booting for the first time, everything on the desktop looked quite large and without animations (it looked nice when I selected the "try Ubuntu" before installing), and when I tried to update the system it reported this bug and prompted me to come here.

If the report lacks any system info I will be happy to provide.

update.1: tried to repeat the installation process and the same thing happened.
update.2: after trying to update with "Software updater" a message appeared with "configuring shim-signed" on the left, and "install grub" with my disk listed below. Selecting the option only shows another option to "continue without installing grub" or something similar.
update.3: performing partial upgrade did not help with any of the visual problems.
update.4: cleaned up the partitions with gparted because of message about "grub" (deleted the big one, and the tiny one, formatting to ext4). Nothing changed.
update.5: installed without third party software. Got the same errors about shim-signed and dpkg, HOWEVER desktop looke just like the "try Ubuntu" and things appear to be in order. Looks like this is something to do with third party, will check the desktop section...
update.6: tried "echo $XDG_SESSION_TYPE" in Ubuntu with third party software and desktop messed up, and the result was "x11". The same command returned "wayland" whith the installation without the software.
update.7: just in case there is some relation between the problems, when installing 20.10, the installer crashes and directs me to the "resolved" bug report in this address: https://bugs.launchpad.net/ubuntu-cdimage/+bug/1871268
update.8: looking up what shim-signed is about, I noticed it is related to "grub". In case this info is of any use: all my previous attempts to install Ubuntu (multiple versions, throughout like 2 years) alongside Windows have failed. The installer does not show the "install alongside Windows" (my bios only has uefi+legacy, and not just legacy option), and manually allocating things has never made "grub" accessible, and windows always boots up first. In every system upgrade, additionally, the installer complains about grub.

As instructed on the submission page, here are the versions of the packages:

Checking for the version of "dpkg" on terminal it gave me this:
"Installed: 1.20.9ubuntu1
  Candidate: 1.20.9ubuntu1
  Version table:
 *** 1.20.9ubuntu1 500
        500 http://br.archive.ubuntu.com/ubuntu hirsute/main amd64 Packages
        100 /var/lib/dpkg/status"

Checking for the version of "shim-signed" on terminal I got this:
"Installed: 1.47+15.4-0ubuntu2
  Candidate: 1.47+15.4-0ubuntu2
  Version table:
 *** 1.47+15.4-0ubuntu2 500
        500 http://br.archive.ubuntu.com/ubuntu hirsute-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     1.46+15.4-0ubuntu1 500
        500 http://br.archive.ubuntu.com/ubuntu hirsute/main amd64 Packages"

ProblemType: Package
DistroRelease: Ubuntu 21.04
Package: shim-signed 1.47+15.4-0ubuntu2
ProcVersionSignature: Ubuntu 5.11.0-22.23-generic 5.11.21
Uname: Linux 5.11.0-22-generic x86_64
.proc.sys.kernel.moksbstate_disabled: Error: [Errno 2] No such file or directory: '/proc/sys/kernel/moksbstate_disabled'
ApportVersion: 2.20.11-0ubuntu65
Architecture: amd64
BootEFIContents:
 BOOTX64.CSV
 grub.cfg
 grubx64.efi
 mmx64.efi
 shimx64.efi
CasperMD5CheckResult: pass
Date: Fri Jun 25 18:19:29 2021
EFITables:
 jun 25 18:25:43 helena-MS-7918 kernel: efi: EFI v2.31 by American Megatrends
 jun 25 18:25:43 helena-MS-7918 kernel: efi: ESRT=0xcef6a998 ACPI 2.0=0xce7aa000 ACPI=0xce7aa000 SMBIOS=0xf05b0 MOKvar=0xcb19c000
 jun 25 18:25:43 helena-MS-7918 kernel: secureboot: Secure boot disabled
 jun 25 18:25:43 helena-MS-7918 kernel: esrt: Reserving ESRT space from 0x00000000cef6a998 to 0x00000000cef6a9d0.
 jun 25 18:25:43 helena-MS-7918 kernel: secureboot: Secure boot disabled
ErrorMessage: installed shim-signed package post-installation script subprocess returned error exit status 1
InstallationDate: Installed on 2021-06-25 (0 days ago)
InstallationMedia: Ubuntu 21.04 "Hirsute Hippo" - Release amd64 (20210420)
Python3Details: /usr/bin/python3.9, Python 3.9.4, python3-minimal, 3.9.4-1
PythonDetails: N/A
RelatedPackageVersions:
 dpkg 1.20.9ubuntu1
 apt 2.2.3
SecureBoot: 6 0 0 0 0
SourcePackage: shim-signed
Title: package shim-signed 1.47+15.4-0ubuntu2 failed to install/upgrade: installed shim-signed package post-installation script subprocess returned error exit status 1
UpgradeStatus: No upgrade log present (probably fresh install)

[Steve Langasek (vorlon)]

The shim-signed installation error is caused by a failure with your firmware preventing the package from accessing EFI variables.

But it is unrelated to the problem you're reporting regarding third-party software installation. For that, we should reassign this bug to ubiquity.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.