Dont use KDE/QT… it’s not OSS.
Can you point where it’s not OSS?
QT ( free edition ) is FOSS and can only be used in FOSS projects, it’s under LGPL license.
If you want to do proprietary stuff you got a QT comercial version and extra tooling to go along with, which you gotta pay a license.
The Qt framework is dual-licensed, available under both commercial and open-source licenses.
About KDE nothing weird to see there.