Currently the scheduling links can account for events in Google Calendars, that have specific start- and end time, blocking any further bookings within the duration of these events.

However, full-day events (without a preconfigured start and end time) are not recognized as blocking the day. Therefore, a scheduling link can still allow events to be created on a day where there's a full-day event going on.

I suggest also taking the full-day events into account when checking for conflicts in a scheduling link.