The on-line and application provided documentation generally (i.e. not just the given version) seems to be as if the fix mentioned in: https://bugreports.qt.io/browse/QTCREATORBUG-12054 is no longer present. E.g. consider https://doc.qt.io/qt-6/qmake-variable-reference.html there is no mention of OTHER_FILES.
This is an oversight as unless one knows about this variable there is no way (AFAICT) to add extra file, that are NOT used by the project per se, but which are to be associated with it, e,g, CI/CB files that a non-Qt build system uses but which are not ones that are to be installed (which would go into DISTFILES).