READLER, Circuit Judge. In 2008, Fifth Third Bank began offering a cash-advance program called “Early Access.” The program enabled customers to “advance” money into their checking accounts (otherwise known as a loan). When a deposit was next made into a customer’s account, Fifth Third would withdraw the loan amount plus 10%. Fifth Third disclosed this 10% “transaction fee” in its standard Early Access terms and conditions, which form the contract at the heart of this dispute. In accordance with the requirements of federal law, the bank also disclosed that these loans had a 120% annual percentage rate. But there was a disconnect between these statements: Because the loans were repaid whenever customers next received a deposit into their accounts, the lengths of the loans were variable, meaning that it was impossible to calculate a standard APR for all loans. As a result, the vast majority of customers paid an APR higher than 120%. Based on this allegedly misleading APR term, William Klopfenstein sued the bank for breach of contract on behalf of a class of Early Access users. At trial, a jury agreed with Klopfenstein that Fifth Third breached the contract but, in the end, found that the bank was not liable for the breach due to the voluntary-payment defense, an Ohio law equitable defense to a breach-of-contract claim. See State ex rel. Dickman v. Defenbacher, 86 N.E.2d 5, 7 (Ohio 1949) (per curiam). As the Ohio courts have explained the defense, if a plaintiff “with full knowledge of the relevant facts” pays the defendant, “such payment cannot be recovered merely because the person who made the payment mistook the law as to his liability to pay.” City of Cleveland v. Ohio Bureau of Workers’ Comp., 109 N.E.3d 84, 114–15 (Ohio Ct. App. 2018) (quoting Dickman, 86 N.E.2d at 7) (City of Cleveland I), rev’d on other grounds, 152 N.E.3d 172 (Ohio 2020) (City of Cleveland II). On appeal, the class contends that Fifth Third could not assert the voluntary-payment defense under Ohio law because the class members made a mistake of fact, not law. Ohio’s cases on the matter, however, point in all directions. As a result, we sua spontecertify to the Supreme Court of Ohio the questions set forth below in accordance with Supreme Court of Ohio Rule of Practice 9.02.