Found a work around explained in step 2 here https://www.tenorshare.com/ios-file-transfer/how-to-sync-google-calendar-to-iphone-and-ipad.html Basically uncheck the shared calendars from this location. http://www.google.com/calendar/iphoneselect This is different from unchecking via the native iOS Calendar App. It’s certainly an iOS 16 issue.