Did you specifically ask the bank to disable overdraft protection? They can be really weaselly about turning it off. They HAVE to turn if off. By law.

https://www.fdic.gov/resources/consumers/consumer-news/2021-12.html

In general, for debit card transactions at ATMs or at merchants, consumers must opt-in, or agree up front, that the bank can charge you an overdraft fee for any debit card transaction that overdraws the account. If you don’t opt-in, you can’t be charged a fee. However, your bank may refuse your purchase if it will overdraw your account.