[SOLVED] The issue has to do with Zorin OS 17.3 which is not supported by Snap version of Fwupd. I ran:
sudo apt update
&& fwupdmgr refresh --force
&& fwupdmgr get-updates
&& fwupdmgr update
in my other OS (Linux Mint Mate 22.1) and it updated UEFI dbx to the current (20241101) version.
This issue needs to be addressed by the Zorin Development Team.
