/usr/include/KF5/KTextWidgets/ is in libkf5textwidgets-dev 5.28.0-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/KF5/KTextWidgets/KFind
/usr/include/KF5/KTextWidgets/KFindDialog
/usr/include/KF5/KTextWidgets/KPluralHandlingSpinBox
/usr/include/KF5/KTextWidgets/KRegExpEditorInterface
/usr/include/KF5/KTextWidgets/KReplace
/usr/include/KF5/KTextWidgets/KReplaceDialog
/usr/include/KF5/KTextWidgets/KRichTextEdit
/usr/include/KF5/KTextWidgets/KRichTextWidget
/usr/include/KF5/KTextWidgets/KTextEdit
/usr/include/KF5/KTextWidgets/kfind.h
/usr/include/KF5/KTextWidgets/kfinddialog.h
/usr/include/KF5/KTextWidgets/kpluralhandlingspinbox.h
/usr/include/KF5/KTextWidgets/kregexpeditorinterface.h
/usr/include/KF5/KTextWidgets/kreplace.h
/usr/include/KF5/KTextWidgets/kreplacedialog.h
/usr/include/KF5/KTextWidgets/krichtextedit.h
/usr/include/KF5/KTextWidgets/krichtextwidget.h
/usr/include/KF5/KTextWidgets/ktextedit.h
/usr/include/KF5/KTextWidgets/ktextwidgets_export.h