The introduction section of https://www.freebsd.org/releases/12.1R/relnotes.html mentions 12.1-release as a snapshot, rather than a release. I compared this with https://www.freebsd.org/releases/12.0R/relnotes.html to decide this is a documentation bug.
A commit references this bug: Author: gjb Date: Wed Nov 6 15:58:23 UTC 2019 New revision: 53558 URL: https://svnweb.freebsd.org/changeset/doc/53558 Log: Fix the release.type macro. PR: 241730 Submitted by: Andras Farkas Sponsored by: Rubicon Communications, LLC (netgate.com) Changes: head/en_US.ISO8859-1/htdocs/releases/12.1R/share/xml/release.ent
Fixed. Thank you for the report.
Thanks :D