Hi Antonio
There's no reply to you on this thread about this, but I wonder if Airbnb contacted you directly about it?
We've noticed a similar thing... our last transaction was US$50 less, when it arrived at our US$ bank account compared to what Airbnb said they sent, and the previous 3 transactions were also $31 less than expected.
I've just checked through months of earlier transactions but this didn't happen between April and Oct... the first time it occured was a payment sent on 23 October, so it appears to be a relatively new thing - is it Airbnb, or is it the banks - any ideas?