A strong argument for updating the Debian packages to cfengine 3.15 LTS is that upstream will stop supporting and patching the 3.12 LTS branch sometime in early 2021. Upstream will support the latest 3.15 LTS branch until the end of 2022 or early 2023. https://cfengine.com/product/supported-versions/
So cfengine in Debian unstable and testing should update to cfengine 3.15 so that bullseye, when it eventually becomes the new stable, isn't stuck on an unsupported cfengine 3.12.
