Google Calendar one-way sync creating "Free" visibility events instead of "Busy"

We are using the google calendar one-way sync (where we created an entirely new google calendar for this particular board - which works out for us). Every time we create a new item on the board and add a date, it shows up on the new google calendar with a default visibility of FREE, instead of BUSY! This creates a problem because we have our Calendly booking system linked to this new google calendar to check for conflicts. Yet when the events are created they have a default visibility as Free. This occurs for events that have a specific time period of 1 hour. I know all day events defaulting as free is a standard google calendar issue, but we’ve made sure the event is for an hour, so ideally the default visibility is set to busy.
Yes, I could go an manually update the new event every time, but we give out our Calendly link to customers and there isn’t always going to be time to update the events if multiple customers are booking.
I have tried asking Google how I could fix this default visibility issue, but they think the issue lies with
Thoughts on how I can get events I create from my board to add to my google calendar with a default visibility of busy?

We aren’t interested in 3rd party integration solutions at this time.