The most expensive mistake we see in early products isn't bad code. It's data recorded in the wrong shape.
Code is cheap to replace, and a messy service can be rewritten in weeks. The records your product has been quietly piling up cannot. If a system stored that a balance changed but not why, or took a payment without keeping what it was for, that gets very hard to reconstruct later: not by your accountant, not by your support team, not by the engineer who eventually rewrites it. A function you can fix. A field you left unrecorded, you cannot go back and capture.
That is why "we'll clean it up after launch" costs so much more than it sounds like. The cleanup runs while real money and real users are already moving through the system, and every correction has to be made twice, once in the new code, once across the history.
So it's probably worth naming the one thing your product doesn't record today that you'd want to look up a year from now.