You could temporarily lose access to money at a particular bank. You will probably get the money back sooner or later, this could be a problem if all your money is in one place and you need to make an important payment.

Fraud is one way this could happen, but not the only one. Fraudulent withdrawals can usually be reversed but not always immediately. If you want to be very careful, you'd have one account that is only used for the most important payments and nothing else.

It is also possible that the bank will decide to close your account if they deem you suspicious. While they will usually return your money, you will be unable to access it while waiting for them to do so.