https://www.theregister.co.uk/2019/08/06/monzo_pins_reset/

Trendy online-only Brit bank Monzo is telling hundreds of thousands of its customers to pick a new PIN – after it discovered it was storing their codes in plain-text in log files.

As a result, 480,000 folks, a fifth of the bank's customers, now have to go to a cash machine, and reset their PINs.