Holiday hours can be labelled
I know that when holiday hours are set, it overrides all other availabilities.
In the example above,
Oct 26th to Oct 30, 2020is holiday hours which override the individual time slots on November 6, 2020 and November 13, 2020.
But some users might be confused as to why this is the case.
Put a notice
"Holiday Hours"right next to the availability block so it is more visible.