I checked in with one of our Appointments Specialists. If an Appointment is deleted or removed from your Square calendar, it's expected to also be removed from your Google Calendar. If it doesn't update right away, you can try refreshing the Google Calendar sync from your online Dashboard.
Appointments > Settings > Calendar & Booking > click the three dots and select refresh.
Hopefully this helps! But if you're still running into trouble, feel free to reach out to our Team and they can take a further look into it with you.