Welcome page: deploy QML image provider for image:://icon path
923a0a2f dropped KDeclarative::setupEngine(engine) but missed to replace it with the explicit installation of the image provider done by the code, as needed by the usage of Image { source: "image:://icon/kdevelop" }
No idea if there is no other way to show images of themed icons these days, but seems KQuickIconProvider is still in use across Qt6/KF6 places, so possibly not. In any case, this seems to work for now.