Arbitrage exists in the foreign exchange market or all financial markets. Please refer to my blog: Melancholy Hedging, which contains several blog posts about arbitrage trading.
Say what you said alone. You need to see clearly which bank's foreign exchange quotation you copied and pasted. If it is the spot exchange rate (non-forward) of the same bank at the same time, then at this moment, there is indeed the arbitrage opportunity you calculated, but this opportunity is often fleeting, because countless arbitrage capitals use the powerful computing power of computer groups and even servers to capture this arbitrage opportunity, and banks are also monitoring it in real time, which will not allow enough arbitrage spread for a long time (here, a long time is possible). Moreover, when you really trade one by one, the price has already been once. Even if the automation of computer groups and servers is used to capture opportunities and transactions, the extra cost caused by slippage or transaction delay may compress the arbitrage space in the transaction process.