Feed security
Every time a calendar app checks a subscription feed for updates, the subscriber's current Confluence permission on the calendar is checked again. Access in Confluence and access through the feed always match.
Access lost for good. If the subscriber is deactivated, their access to the calendar is removed, or the calendar is deleted, the link is revoked permanently. The feed then reports that it is "no longer available".
A temporary problem. If the check fails for a passing reason, the feed asks the calendar app to try again later. The link is not revoked.
App uninstalled. Uninstalling the app revokes every feed link on the site and deletes the stored copies of the feeds.
#Related
How it actually behaves.
