There is an Airbnb member who would like to book our apt from tomorrow (23 October) but I cannot pre-apporve him and he cannot book. The days got blocked on my calender and the system says there is some kind of verification going on. The guest already has one good review from another host.
Sounds like you have another guest currently going through verification who has (by coincidence) requested the same dates. Airbnb gives the guest going through verification about 24hs to complete the steps, and in meantime your calendar is blocked to anyone else.