If you're wondering about who can access a particular sub-calendar, you can check. Here's how.
👩💻Reminder: Only calendar administrators can access calendar settings.
Beneath the access list, there's an option to reset permission for all users and links with access to the sub-calendar. So if there is a security issue, you can quickly change the permission to Not shared or Read-only, for example, to prevent unauthorized access or changes to that sub-calendar. Then, if appropriate, you can review user/link access individually and reset permissions for those who should have a higher level of access to the sub-calendar.