/usr/lib/x86_64-linux-gnu/ is in libkf5sonnet-dev 5.28.0-2.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/x86_64-linux-gnu/cmake/
/usr/lib/x86_64-linux-gnu/cmake/KF5Sonnet/
/usr/lib/x86_64-linux-gnu/cmake/KF5Sonnet/KF5SonnetConfig.cmake
/usr/lib/x86_64-linux-gnu/cmake/KF5Sonnet/KF5SonnetConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/KF5Sonnet/KF5SonnetTargets-debian.cmake
/usr/lib/x86_64-linux-gnu/cmake/KF5Sonnet/KF5SonnetTargets.cmake
/usr/lib/x86_64-linux-gnu/qt5/
/usr/lib/x86_64-linux-gnu/qt5/mkspecs/
/usr/lib/x86_64-linux-gnu/qt5/mkspecs/modules/
/usr/lib/x86_64-linux-gnu/qt5/mkspecs/modules/qt_SonnetCore.pri
/usr/lib/x86_64-linux-gnu/qt5/mkspecs/modules/qt_SonnetUi.pri
/usr/lib/x86_64-linux-gnu/libKF5SonnetCore.so
/usr/lib/x86_64-linux-gnu/libKF5SonnetUi.so