Context

The system dashboard default is public by default and there's no way to change that. Still, showing pages to users without authentication is an expected behavior in Jira, and here's why.

Some types of content in Jira have the option to share with the public, for instance, project issues if Browse project permission is set to it, dashboards if they are shared with the public as well as filters.

However, the content inside these won't be ever displayed if they are not shared with the public.

Suggestion

Even though the content inside these won't be ever displayed if they are not shared with the public, the system dashboard, for example, would still appear on the internet, as it's public

Would be very useful if a functionality gets added to avoid such behavior.