When someone deposits money and withdraws a large amount of winnings, it will make the bank feel suspicious and will investigate your account. Therefore, they should look for other solutions rather than being subject to sanctions from the regulator. So far, people who gamble using crypto have used crypto, so they don't need to use their bank accounts.
If you use fiat casino, there is an official service or platform which is also digital wallet and on the gambling site there will be an admin who can help customers deposit or withdraw money directly into the digital wallet.
This transaction will read like normal transaction in general involving two people or transaction between users of the platform so that it is impossible to suspect or detect that the transaction was carried out with gambling site.
If you use crypto site, it will be even easier and of course you will understand the various ways that every gambler can use in transactions with crypto gambling sites.
But I don't think the bank will ever suspect users who have history of depositing large amounts of money as long as the amount doesn't reach fantastic figure, if it is very large amount, they will probably only be asked for additional tax.
This is what happens in my country, if an account user has deposit limit or balance of large amount, then tax will only be applied, the amount of which can still be said to be quite small.
They don't care what you did to get that much money as long as you don't have bad history like criminal or have history of fraud or anything that violates the law.