@Branka-and-Silvia0
I also have 3 months availibility window. You are right, the multicalender shows at first sight all dates are indefinitely available.
But... when you select 1 or more dates after 5 october (for some reason not 8 oct), it will show in the separate screen they are not availabe because of 3 months availibility window.
So visually it is indeed a glitch, but technically it is OK