KDE - Error when starting configuration from terminal.

Hello.

I got an error when starting this command :

kcmshell5 kcm_desktoptheme
org.kde.kcoreaddons: Error loading plugin "kcm_desktoptheme" "The shared library was not found." 
Plugin search paths are ("/usr/lib64/qt5/plugins", "/usr/bin") 
The environment variable QT_PLUGIN_PATH might be not correctly set
file:///usr/lib64/qt5/qml/org/kde/kirigami.2/private/globaltoolbar/BreadcrumbControl.qml:63:59: Unable to assign QQuickItem to Page_QMLTYPE_40
file:///usr/lib64/qt5/qml/org/kde/kirigami.2/templates/AbstractApplicationHeader.qml:46:25: Unable to assign QQuickItem to Page_QMLTYPE_40
qt.svg: link XMLID_5_ hasn't been detected!

Effectively the plugin “kcm_desktoptheme” does not exists.
But the desktop “theme editor - System settings module” but nevertheless open itself.

Same kind of error with :

user_install@ASUS-G731GV-JC:~> kcmshell5 kcm_lookandfeel
org.kde.kcoreaddons: Error loading plugin "kcm_lookandfeel" "The shared library was not found." 
Plugin search paths are ("/usr/lib64/qt5/plugins", "/usr/bin") 
The environment variable QT_PLUGIN_PATH might be not correctly set
file:///usr/lib64/qt5/qml/org/kde/kirigami.2/private/globaltoolbar/BreadcrumbControl.qml:63:59: Unable to assign QQuickItem to Page_QMLTYPE_41
file:///usr/lib64/qt5/qml/org/kde/kirigami.2/templates/AbstractApplicationHeader.qml:46:25: Unable to assign QQuickItem to Page_QMLTYPE_41

Any comment is welcome.

Presumably, it is not intended to be directly called.