Currently, when performing the release branch creation step of the release plan (https://dev.xwiki.org/xwiki/bin/view/ReleasePlans/ReleasePlanHelp#HOnlycreatethenewstablebranches), the package versions are not updated to the next development version on the master branch. It happened only once when branching for the release of 18.0.0RC1.
https://github.com/xwiki/xwiki-dev-tools/pull/18