Dist upgrade blocked by missing Perl package

I'm trying to upgrade 22 LTS to 24 LTS by running sudo do-release-upgrade -d but I get this message:

Checking for a new Ubuntu releasePlease install all available updates for your release before upgrading.

sudo apt list --upgradable output:

Listing... Donegrub-efi-amd64-bin/oldoldstable 2.06-3~deb10u1 amd64 [upgradable from: 2.06-2ubuntu14.4]libfile-fcntllock-perl/oldoldstable 0.22-3+b5 amd64 [upgradable from: 0.22-3build7]

sudo apt upgrade output:

Reading package lists... DoneBuilding dependency tree... DoneReading state information... DoneCalculating upgrade... DoneGet more security updates through Ubuntu Pro with 'esm-apps' enabled:  python2.7-minimal libheif1 imagemagick libpathplan4 graphviz libavdevice58  libgvpr2 libgvc6 ffmpeg libopenexr25 libpostproc55 libcgraph6  libmagickcore-6.q16-6-extra libcdt5 libavcodec58 libmagickwand-6.q16-6  libavutil56 imagemagick-6.q16 libswscale5 xrdp libmagickcore-6.q16-6  liblab-gamut1 libswresample3 imagemagick-6-common libavformat58 python2.7  libde265-0 libpython2.7-minimal libpython2.7-stdlib libavfilter7Learn more about Ubuntu Pro at https://ubuntu.com/proThe following packages have been kept back:  grub-efi-amd64-bin libfile-fcntllock-perl0 upgraded, 0 newly installed, 0 to remove and 2 not upgraded.

sudo apt upgrade grub-efi-amd64-bin libfile-fcntllock-perl output:

Reading package lists... DoneBuilding dependency tree... DoneReading state information... DoneCalculating upgrade... DoneSome packages could not be installed. This may mean that you haverequested an impossible situation or if you are using the unstabledistribution that some required packages have not yet been createdor been moved out of Incoming.The following information may help to resolve the situation:The following packages have unmet dependencies: libfile-fcntllock-perl : Depends: perlapi-5.28.0 shim-signed : Depends: grub-efi-amd64-signed (>= 1.187.2~) but it is not going to be installed or                        grub-efi-arm64-signed (>= 1.187.2~) but it is not installable

A bit of searching revealed that perlapi is (it appears) included in perl-base.So next is: sudo apt install perl-base=5.28.0:

Reading package lists... DoneBuilding dependency tree... DoneReading state information... DonePackage perl-base is not available, but is referred to by another package.This may mean that the package is missing, has been obsoleted, oris only available from another sourceHowever the following packages replace it:  perl-modules-5.28 libperl5.28 perl:i386 libperl5.34:i386 perl-modules-5.34 perl libperl5.34

sudo apt install perl-modules-5.28 libperl5.28 output:

Reading package lists... DoneBuilding dependency tree... DoneReading state information... DoneThe following NEW packages will be installed:  libperl5.28 perl-modules-5.280 upgraded, 2 newly installed, 0 to remove and 2 not upgraded.Need to get 6,768 kB of archives.After this operation, 46.2 MB of additional disk space will be used.Get:1 http://ftp.us.debian.org/debian buster/main amd64 perl-modules-5.28 all 5.28.1-6+deb10u1 [2,873 kB]Get:2 http://ftp.us.debian.org/debian buster/main amd64 libperl5.28 amd64 5.28.1-6+deb10u1 [3,894 kB]Fetched 6,768 kB in 3s (2,664 kB/s)      Selecting previously unselected package perl-modules-5.28.dpkg: warning: files list file for package 'grub-efi-amd64-signed' missing; assuming package has no files currently installeddpkg: warning: files list file for package 'grub2-common' missing; assuming package has no files currently installeddpkg: warning: files list file for package 'grub-pc-bin' missing; assuming package has no files currently installeddpkg: warning: files list file for package 'grub-pc' missing; assuming package has no files currently installeddpkg: warning: files list file for package 'grub-common' missing; assuming package has no files currently installeddpkg: warning: files list file for package 'grub-gfxpayload-lists' missing; assuming package has no files currently installeddpkg: warning: files list file for package 'grub-efi-amd64-bin' missing; assuming package has no files currently installed(Reading database ... 415876 files and directories currently installed.)Preparing to unpack .../perl-modules-5.28_5.28.1-6+deb10u1_all.deb ...Unpacking perl-modules-5.28 (5.28.1-6+deb10u1) ...Selecting previously unselected package libperl5.28:amd64.Preparing to unpack .../libperl5.28_5.28.1-6+deb10u1_amd64.deb ...Unpacking libperl5.28:amd64 (5.28.1-6+deb10u1) ...Setting up perl-modules-5.28 (5.28.1-6+deb10u1) ...Setting up libperl5.28:amd64 (5.28.1-6+deb10u1) ...Processing triggers for man-db (2.10.2-1) ...Processing triggers for libc-bin (2.35-0ubuntu3.8) ...

So I try: sudo apt upgrade libfile-fcntllock-perl to fix the held back packages one at a time and get:

Reading package lists... DoneBuilding dependency tree... DoneReading state information... DoneCalculating upgrade... DoneSome packages could not be installed. This may mean that you haverequested an impossible situation or if you are using the unstabledistribution that some required packages have not yet been createdor been moved out of Incoming.The following information may help to resolve the situation:The following packages have unmet dependencies: libfile-fcntllock-perl : Depends: perlapi-5.28.0E: Broken packages`

Following the link provided on the aforementioned search I see that there is no 5.28 package listed.

So I'm feeling kind of stuck. Any suggestions are gratefully received.