>We will be switching to new signing keys along with the overhaul of the signing and verification process. As a result, current CalyxOS users will not be able to receive further security software updates until this process is in place.
really makes you wonder what else has happened

you tell us
if you're implying this is to include sketchy changes there'd be no need to change signing keys
keep in mind changing signing keys forces users to delete all user data (actually, you can build android with a specific patch to avoid this but it seems like that's not going to be done, see https://wiki.lineageos.org/signing_builds#using-a-migration-build)