According to the document, that includes social security numbers and account balances; account transactions and income; and credit scores and checking account information.
This is definitely the kind of information that any bank would need to have for its loan customers. But it doesn’t necessarily seem like information that it would need to share with third parties—especially for marketing purposes. But according to the document, it can:
A screenshot from a recent Citizen One customer notice shows that they have the right to share customer's personal information for marketing purposes
According to the letter, Citizens use your information to market its own products, and share your information so that “affiliates” can also market to you. Citizens Bank wasn’t immediately available to explain the difference between “affiliates” and “nonaffiliates,” or how often it shares customers’ personal information.