On a fresh install of 12.0-RELEASE, freebsd-update upgrade gave me the following message:
WARNING: FreeBSD 12.0-RELEASE is approaching its End-of-Life date.
It is strongly recommended that you upgrade to a newer
release within the next 2 months.
However, there is no newer release for me to move to. 12.1 is still in the beta stage and isn't due for release for another month.
freebsd-upgrade should check for the existence of a newer release before printing the warning about end of life.