The Qt Data Visualization module has Qt Design Studio integration for the 3D graph types (those that inherit AbstractGraph3D). The Qt Graphs module have the same types, but the Qt Design Studio integration is missing:

The main reason seems to be because qtgraphs.metainfo is not shipped (https://github.com/qt/qtgraphs/blob/6.6.1/src/graphs/qml/designer/qtgraphs.metainfo )

• C:\Qt\6.6.1\msvc2019_64\qml\QtDataVisualization\designer\qtdatavisualization.metainfo is deployed
• C:\Qt\6.6.1\msvc2019_64\qml\QtGraphs\ and its subfolders are missing the *.metainfo file