I got information from my Helpdesk that this addon is causing some errors in Moodle (CRON), which can lead to unstable platform working.
The real-time interpretation of a free hand drawing probably requires the activation of an appropriate cronjob, separate from that which runs according to the moodle cron, using a cron.php script, even preferably running on a separate application server
to take load from the frontend servers.
No sweat for an experienced developer, but still a bit difficult for me.