General

• Made the “2024” theme variants the default in
  Preferences > Environment > Interface
  (QTCREATORBUG-32400)
• Updated icons
• Improved support for extracting archives
  (QTAIASSIST-169)
• Added a Courses tab to Welcome mode
• Added tab completion to the locator
• Extensions
  • Moved the default extension registry to
    https://github.com/qt-creator/extension-registry
    (submissions not open to the public yet)
  • Added the option to configure multiple extension registries in
    Preferences > Extensions > Browser
  • Added the dependencies and supported platforms of extensions that are not
    installed to their details
  • Added version selectors for extensions that are not installed
  • Added support for dropping extension archives onto Extensions mode
    (Documentation)

Full list of features and fixes: https://github.com/qt-creator/qt-creator/releases/tag/v17.0.0-beta2