Ha, we should have mentioned it on the tutorial. You can echo those messages with the gz topic CLI. You can also view them on the GUI with Window → Topic Visualization.
I’m not sure what the question is. What are the LIDAR’s update rates as set on SDF?
I don’t have any immediate insights for you here, I’d have to research a bit on how the ros2 CLI and rviz2 are calculating the frequency.