I am sorry but is this number accurate? It is incredibly tiny compared to what is expected for a flagship distribution like Ubuntu, especially if we take previous statistics into account.
In 2013 Canonical said that it is expected to have 18 million desktop users: https://web.archive.org/web/20120614123643/http://www.theinquirer.net:80/inquirer/news/2173243/canonical-expects-ubuntu-pre-installed-million-pcs-2013
How come 10 years later, we now have only 6 million?
The methodology could be different of course, but such a huge difference should be enough indicator that there is something wrong with it. Perhaps depending on the package update mechanism is not wise.