While experimenting with MagicMirror, encountered a weird phenomenon where the Google iCal feed used by either the default Calendar module or the MMM-CalendarExt module showed phantom events that were not visible on Google default calendar interface.
As usual Google is the answer, tried the steps below and found that these were due to recurring events setup 10 years ago that never showed up in current Calendar views but were included in the feed.
Steps to find your Calendar ID:
Login to Calendar (on desktop/laptop), in the calendar list on the left, click the down-arrow button next to the appropriate calendar, then select Calendar settings.- In the Calendar Address section, locate the Calendar ID listed next to the XML, ICAL and HTML buttons.
Steps to find the event IDs for deleted events:Go to this Calendar API link: https://developers.google.com/apis-explorer/#p/calendar/v3/calendar.events.list?maxResults=1000&showDeleted=true&_h=1&
Click on the “Authorize requests using OAuth 2.0” button on the right top section of the page (It is off by default)
Click on Authorize on the “Select OAuth 2.0 scopes” dialog
Enter the Calendar ID in the calendarId text box
Click the blue Execute button
Use your browser search functionality to search for “cancelled”. This allows you to search for deleted events
Locate the specific events with “status” as “cancelled” (deleted events) which you think have been incorrectly deleted
For these events only, note the value for the “id” field (it will be a long alphanumeric string)