The headline isn't an accurate quote. 9to5Mac, quoting the Wall Street Journal:

When Goldman Sachs and Apple launched their joint savings account in April, Goldman held a town hall at its headquarters, where bank executives talked it up. One executive had a different message shortly afterward. “We should have never done this f—ing thing,” the Goldman partner told colleagues.

"Mistake" isn't actually even part of the quote. The headline also implies that this is an observation made by looking back on it, rather than a comment made at launch by someone who may not have even been involved in the project.