The bank remembering it is great if you’ve entered it correctly, but if you enter it incorrectly and the bank remembers it that has the potential to make the problem worse. Some users will see their payment hasn’t gone through and will make the payment again, causing extra work for the Freetrade team to manually sort out.
Making it easy for users to enter it correctly will reduce these kinds of problems. It will also make the user feel less intimidated by the app if they don’t have to pass a difficult memory test right off the bat.
I recognise that once you’re in and set up this stops mattering, but Freetrade will do better if there isn’t this kind of choke point filtering out some of their users before they become customers.