Just getting up to speed with the 2021.3 release…
… but there is a 2021.6.x (default) branch on corteza-server
What is the difference / what is the development plan?
Each release version is based on its own branch, so the 2021.3 release resides on the 2021.3.x branch, the 2020.12 release resides on the 2020.12.x branch (and so on).
The 2021.6.x branch is the home of the in-progress 2021.6 release, and once the 2021.6 is released, a new 2021.9.x branch will be created where we will be developing the 2021.9 release.