The Key Exchange Key (KEK) acts as an authority that allows Microsoft to update the other databases, like the DB and DBX that tell your computer which bootloaders are safe.
Microsoft is taking its time with the boot certificate rollout, but you don't have to. Activate the latest UEFI CA 2023 right now.
Some people are deeply reluctant to install software updates, and there can be valid reasons for that. Most updates are beneficial, of course -- they're solving bugs, fixing security holes, or adding ...