Currently there is experiemental Docker image in https://hub.docker.com/r/taboriso/docker-raspberrypi-64-bit and Qt Creator is configured to fetch it from there as implemented in https://codereview.qt-project.org/c/qtsdk/tqtc-qtsdk/+/408521. 

Now new Docker Image for Qt 6.4.x or later needs to be uploaded to https://git.qt.io/docker/for-qt-creator  and Creator configuration scripts need to be modified to fetch the image from there.