/usr/include/KF5/KActivities/ is in libkf5activities-dev 5.28.0-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/KF5/KActivities/KActivities/
/usr/include/KF5/KActivities/KActivities/ActivitiesModel
/usr/include/KF5/KActivities/KActivities/Consumer
/usr/include/KF5/KActivities/KActivities/Controller
/usr/include/KF5/KActivities/KActivities/Info
/usr/include/KF5/KActivities/KActivities/ResourceInstance
/usr/include/KF5/KActivities/KActivities/Version
/usr/include/KF5/KActivities/kactivities/
/usr/include/KF5/KActivities/kactivities/activitiesmodel.h
/usr/include/KF5/KActivities/kactivities/consumer.h
/usr/include/KF5/KActivities/kactivities/controller.h
/usr/include/KF5/KActivities/kactivities/info.h
/usr/include/KF5/KActivities/kactivities/kactivities_export.h
/usr/include/KF5/KActivities/kactivities/resourceinstance.h
/usr/include/KF5/KActivities/kactivities/version.h