@Rowena29I list multiple properties on multiple platforms - TripAdvisor, AirBnB, HomeAway, Booking.com etc - and that means a lot of calendar syncing. The ical data varies between each platform and does not always include guest or booking information - it can say something like "Closed - Not available". So, in theory, AirBnB will not know whether the event (block) is for a guest booking or closed for maintenance or whatever.
I should point out that Booking.com calendar sync is very very unreliable - it's broken - it doesn't always export events, sometimes merges events (so 2 bookings back to back show as one booking), sometimes doesn't import events, and sometimes loses calendar sync information so it shows that you've never set it up in the first place. Always block manually if using Booking.com.
As for the damage claims, it might be wise to rethink that - have a read of the various discussions here about retaliatory reviews after hosts claim on damage deposits. You may be justified in claiming £50 or $50, but you might not win the claim and could get a 1* review, which ends up costing you more than you were claiming ..... of course, with the unfairness of this system, it's up to each host how they set up and handle things .....