Ubuntu keeps rebooting and displays message that safeboot dbx has been updated

[ericmarceau]

I don’t know much here, but have you looked at the page

• Chain of Trust - safeboot

At the bottom right, there is a link pointing to

• "safeboot subcommands → "

There is also this reference:

• GitHub - rowanmoul/ArchSecureDualBoot: A system for dual booting Arch Linux and Windows with disk encryption enabled on both. · GitHub

You might find something there that could help.