This page is about maintaining the official binary package repository of postmarketOS. It does not relate to the local package repository that
pmbootstrap creates when compiling packages. So most people will not need this.
There are KDE packages, which need to be rebuilt after each QT upgrade:
$ pmbootstrap pkgrel_bump kwayland kwin plasma-framework kdeclarative frameworkintegration plasma-integration
See pmaports#130 for an idea to automatize this and for more information.