Now we get to the third address. This one is the address where the 0.005 BTC were sent at each transaction by the addresses mentioned above. Wallet Explorer identifies that those 0.005 BTC transactions were sent to CoinJoin Mess. I don't know what this CoinJoin Mess could be. Could it be a particular implementation of CoinJoin, which has the name "CoinJoin Mess"? Or is it a normal CoinJoin transaction and the "Mess" part is due to the way Wallet Explorer shows these transactions...?
There's no such thing as a CoinJoin Mess. Since WalletExplorer groups transactions by wallet names as opposed to address, the coinjoin must have confused it and it couldn't figure out where the coins were sent to (as expected from CoinJoin).
Did you try checking how many transactions are associated with these addresses? If they were used thousands of times it's definitely an exchange as no mere mortal can use an address that many times.
This address in particular has 7800+ transactions.
1A8JiWcwvpY7tAopUkSnGuEYHmzGYfZPiq