In the search bar calendar, dates close to today appear greyed out and show a "Requires N-day advance booking" message.
Why this happens. These dates are blocked by the Toolkit’s Advance Notice Blocking module. When this module is enabled, dates inside the configured advance-notice period cannot be selected and display the notice as a tooltip.
What you can do. To change this behavior, go to the Toolkit Hub and either adjust the advance-notice hours or disable the module.