Making the Qt 6.6 release significant is that it will also be the newest Qt 6 Long-Term Support (LTS) release. Qt 6.6 does bring a new module, Qt Graphs, offered up in technical preview form this cycle for combining functionality formerly found with the separate Qt DataVisualization and Qt Charts modules.
Qt 6.6 is set to bring many new features including a more robust Wayland compositor experience , support to the Qt GUI Module for direct access to OpenType features of used fonts, the QRhi family of classes for the Qt Rendering Hardware Interface is now fully documented, the Qt Quick Shapes module adds an experimental curve rendering back-end, support for importing PLY files with Qt Quick 3D, initial Render Extensions support for Qt Quick 3D, Qt SQL adds a Mimer SQL plug-in, and Qt TextToSpeech improvements.
More details on the big Qt 6.6 toolkit release via Qt.org .