Found unsuitable Qt version "5.15.16"

Hello,
Version 7.9.0 is OK on FreeBSD, but trying to install 7.9.1 fails during the configuration step with the following message:

-- Found unsuitable Qt version "5.15.16" from /usr/local/lib/qt5/bin/qmake
-- Info: The directories of 3rdparty headers:
/usr/local/include/tcl8.6
/usr/local/include/tk8.6
/usr/local/include/freetype2
/usr/local/include/vtk-9.2
/usr/local/include
/usr/local/ffmpeg4/include
/usr/local/include/draco
-- Info: The directories of 3rdparty libraries:
/usr/local/lib
/usr/local/ffmpeg4/lib

Which version of Qt5 would be accepted?

Remark: USE_QT_FROM_3RDPARTY_DIR is On, and 3RDPARTY_QT_DIR is set to the correct directory.