Mocacinno, do you think it's used directly by the bitfinex owner.. or it is a normal user account on bitfinex?
I am not Mocacinno (even tho i love drinking them), but i am still going to answer your question
Each address owned by bitfinex is 'directly' owned by bitfinex. They just provide their address to a user to deposit to.
It (most probably) is a deposit address, since the concept of a 'mixing address' is unnecessary. It doesn't bring any benefits, just more TX's -> More fees.
The withdrawals from this address about 10-60 minute after deposits do also indicate that it is a 'deposit' address (which is being used to withdraw other customer).