Yep, Qt Quick 3D is available under Qt commercial and GPLv3 license [1]. "New" Qt modules, like for example Qt 3D, are used to be licensed under LGPL and not GPL for the open-source part [2].
But recently they started to change some modules licensing from LGPLv3/Commercial to GPLv3/Commercial [3].
[1] https://doc.qt.io/qt-5/qtquick3d-index.html#license-and-attr... [2] https://doc.qt.io/qt-5/qt3d-index.html#licenses-and-attribut... [3] https://www.qt.io/blog/change-in-open-source-licensing-of-qt...