Tiki 21.0 will be released in February 2020.
It requires PHP 7.2, vs PHP 7.1 for Tiki20.
It is a Long Term Support (LTS) version and will be supported until February 2025 as per the Tiki lifecycle policy
- Added support for https://download.libsodium.org/doc/
Also, see the standard information about Upgrades in Tiki.