Comment # 1 on bug 1206041 from Fabian Vogt

> As another consequence installing both kdsoap-devel and kdsoap-qt6-devel is not possible:

That's intentional - kdsoap does not allow that. See the changelog:

buildsystem - undo co-installability of Qt5 and Qt6 headers.
It would require that kdwsdl2cpp generates #include
<KDSoapClient-qt6/KDSoapJob.h>
which in turn would break the build of KDSoap itself, so this gets tricky.