What happens when I re-sync data with Google after the sync was disabled or sync settings were changed?

When you re-sync data with Google after the sync was disabled, or after you changed settings about what needs to be synced, all the existing events synced to Google Calendar are cleared, and then re-synced again. The re-sync includes events on the last 14 days.

In addition, even without a re-sync, whenever there is a change to an event (ex. a new booking, or changed details in a booking), the event is re-synced to Google Calendar.