Badger switched to CalVer along with Dgraph in March 2020.
To overcome the issue of working with Go modules, we hijacked the syntax of SemVer. So all versions will be rooted at v2 from now on. v2.2007.2 is the latest. For example, if there is to be a release in March this year, the version will be v2.2103.1.
As for schedule, I think there was supposed to be a Badger v2.2011.1 but we skipped that release. I think @ibrahim can give you a better idea of when the next release will drop.
Hope that answers your question.