I am using qt apt installed version.

developer@LAPTOP ~/repos/$ qmake -v
QMake version 3.1
Using Qt version 5.15.8 in /usr/lib/x86_64-linux-gnu

developer@LAPTOP ~/repos/$ qmake6 -v
QMake version 3.1
Using Qt version 6.4.2 in /usr/lib/x86_64-linux-gnu

-- Found libdw: /usr/lib/x86_64-linux-gnu/libdw.so
-- Found libbfd: /usr/lib/x86_64-linux-gnu/libbfd.so
-- Found libdwarf: /usr/lib/x86_64-linux-gnu/libdwarf.so
-- Found Backward: /home/developer/repos/GammaRay/3rdparty/backward-cpp
-- Building GammaRay 2.99.50 (revision: 5269d6e) in Debug mode
CMake Error at /usr/lib/x86_64-linux-gnu/cmake/Qt6Scxml/Qt6QScxmlEcmaScriptDataModelPluginTargets.cmake:96 (message):
The imported target "Qt6::QScxmlEcmaScriptDataModelPlugin" references the
file

 "/usr/lib/x86_64-linux-gnu/qt6/plugins/scxmldatamodel/libqscxmlecmascriptdatamodel.so"

but this file does not exist. Possible reasons include:

• The file was deleted, renamed, or moved to another location.

• An install or uninstall procedure did not complete successfully.

• The installation package was faulty and contained

  "/usr/lib/x86_64-linux-gnu/cmake/Qt6Scxml/Qt6QScxmlEcmaScriptDataModelPluginTargets.cmake"

but not all the files it references.

Call Stack (most recent call first):
/usr/lib/x86_64-linux-gnu/cmake/Qt6Scxml/Qt6QScxmlEcmaScriptDataModelPluginConfig.cmake:61 (include)
/usr/lib/x86_64-linux-gnu/cmake/Qt6/QtPublicPluginHelpers.cmake:439 (include)
/usr/lib/x86_64-linux-gnu/cmake/Qt6Scxml/Qt6ScxmlPlugins.cmake:5 (__qt_internal_include_plugin_packages)
/usr/lib/x86_64-linux-gnu/cmake/Qt6Scxml/Qt6ScxmlConfig.cmake:133 (include)
CMakeLists.txt:473 (find_package)