/usr/lib/ is in libqtav-dev 1.12.0+ds-4build3.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/x86_64-linux-gnu/libQt5AV.so
/usr/lib/x86_64-linux-gnu/libQt5AVWidgets.so
/usr/lib/x86_64-linux-gnu/libQtAV.so
/usr/lib/x86_64-linux-gnu/
/usr/lib/x86_64-linux-gnu/libQtAV.prl
/usr/lib/x86_64-linux-gnu/libQtAVWidgets.prl
/usr/lib/x86_64-linux-gnu/qt5/
/usr/lib/x86_64-linux-gnu/qt5/mkspecs/
/usr/lib/x86_64-linux-gnu/qt5/mkspecs/features/
/usr/lib/x86_64-linux-gnu/qt5/mkspecs/features/av.prf
/usr/lib/x86_64-linux-gnu/qt5/mkspecs/features/avwidgets.prf
/usr/lib/x86_64-linux-gnu/qt5/mkspecs/modules/
/usr/lib/x86_64-linux-gnu/qt5/mkspecs/modules/qt_lib_av.pri
/usr/lib/x86_64-linux-gnu/qt5/mkspecs/modules/qt_lib_avwidgets.pri
/usr/lib/x86_64-linux-gnu/libQtAVWidgets.so