At the moment customers are in some cases using QML streams to render text (especially smaller text) because Qt 3D Studio text labels are not on par with quality. This is critical as to get good performance you want to minimize switching between 3D/2D rendering and text labels should be rendered inside Qt 3D Studio with good enough quality to use as it is. Even the weight of the font is different in Qt 3D Studio, one needs to use 2x scaling to achieve same weight look as with Qt Quick (with worse non-RGB AA).

Most likely the difference is in the fact that Qt Quick uses distance field rendering of glyphs and that produces better result.