When you connect a Google or Microsoft account to CalendarBridge, we only request the bare minimum access/permissions needed for syncing calendars. This includes your basic profile information and the ability to read and write your calendars. We do not request access to your contacts, your email, your files, or anything else. Just basic profile info and calendars. (To see the actual permissions requested see Connecting Google calendars and Connecting Microsoft calendars)
As for the calendar data to which we have access, the only thing we do with it is copy it between your accounts as instructed by your sync connections. We do not store or analyze any of it. Check out our terms of service to learn more.