I wanted to share this solution as I wasn't able to find it when searching through the Zoho community and via web search.

The issue: When requestor books a meeting through Zoho Bookings, the requestor receives a confirmation email from both Bookings and from Google Calendar when Google Calendar is integrated. Multiple email confirmations create confusion for the requestor, and it reveals my personal Google email address since it's sync'ed to my personal Google calendar.

The solution: Under Integration -> Add Bookings to Calendar -> Your Google Calendar, there's a checkbox at the bottom titled "Set as default to add invite to customer calendar."  The wording on this is confusing.  But if you UNCHECK this, the requestor of the booking is NOT added as a participant in your Google Calendar.  This successfully creates the event both in your Zoho Bookings and in your Google Calendar, and only sends the invitation and reminders from Zoho Bookings.

Google Calendar has a "feature" in that if the participant is not a "gmail.com" domain user, the system automatically sends notifications to the event participant.  If you checked this checkbox, the requestor is added as a participant in your Google Calendar event and would receive the Google notifications in addition to the Bookings notifications.

I hope this solution helps someone who is confused as I was on how to stop triggering multiple email confirmation and notifications using Zoho Bookings and integrating with Google Calendar.