Wix Booking hidden service gives 404 when linked to directly

When hiding a service, I noticed recently that the Booking widget for that service shows the service as “Unavailable” and the booking flow entry URL gives a 400 as long as the service is hidden.
Is this intentional?
We need to have promoted services that should not be shared publicly (we have price reduced promotional services). This is why we need to hide certain services so that they will not appear under “Book Online”
Could someone please advise?

Hi,
How do you hide the service? Do you use code or hide the page?
Can you please send us some screenshots and more information about the scenario? The site URL can be useful too.

Thanks,
Tal.