So I almost have zero balance in this wallet (which is on an exchange if that matters), but it shows the balance as 0.43 ether. Is it a problem with etherscan website or I'm missing something?
If the exchange you're using is a centralized exchange, then this makes perfect sense. When you deposit coins to an exchange, the address they give you usually isn't your wallet, it's one of their collection wallets. They'll often sweep from these wallets when they get full enough and send the funds to their hot and/or cold wallets. They also usually don't send from the same wallet that they have you send to, so the balances of the address you send to usually wont match your balance on the exchanges internal ledger.