Regularly check your Nextcloud instance for vulnerabilities
Nextcloud is being developed so quickly that you hardly notice it anymore. While there have been no known security vulnerabilities in the past, it is always better (and best practice) to be paranoid and cautious rather than having to sweep up the mess later.
Nextcloud assigns school grades for your Nextcloud instance at scan.nextcloud.com. The grades are A+ (you are a model student) and F (take urgent action!). However, there is a need for action from grade C at the latest.
Regardless of the fact that constantly entering your own page is annoying, the result of the query is cached, so you don't necessarily have the current result.
For this I have written a small script that triggers each query again and can be implemented in the monitoring.
Feel free to use the script for your own Icinga2/Nagios instance or as a cron/systemd timer for email notification if you don't have a monitoring server.