Asus has pushed a new software update to the ZenFone 6. It contains an updated security patch level - albeit only up to November 2019 - as well as some new UI tweaks and bug fixes. It is intended for the global and Indian (or 6z) versions of this phone.
https://www.notebookcheck.net/Asus-latest-update-for-the-ZenFone-6-6z-has-the-November-2019-security-patch.448169.0.html