QT设置QT_DEBUG_PLUGINS无法打印报错信息

Question

为什么设置环境变量 export QT_DEBUG_PLUGINS=1后，不能打印类似如下的报错信息呢？

Found metadata in lib /usr/lib64/qt5/plugins/platforms/libqxcb.so, metadata=
{

"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
    "Keys": [
        "xcb"
    ]
},
"className": "QXcbIntegrationPlugin",
"debug": false,
"version": 329218

}