4 challenges, from 14 reviews on iOS and Android.
Duolingo
just take hundreds of dollars off your card with no consent and no way to get it back
Build itA trial that names the charge date and the amount before it starts, and again before it lands.
Start itA subscription record kept outside whoever is selling the subscription.
Study itHow many people who believe they cancelled were still charged?
Write itThe week between cancelling and being charged for the year.
Early signal
Duolingo
my app is broken and it's putting me at a huge disadvantage
Build itA free tier metered by time practised rather than by mistakes made.
Start itPractice software where the daily amount is fixed and paid for once.
Study itWhat happens to a practice habit when a meter sets the session length?
Write itThe lesson that stops in the middle of itself.
Early signal
Duolingo
it also won't load kana or other character / writing lessons
Build itA lesson that is fully on the device before it starts.
Start itOffline-first practice for people with unreliable connections.
Study itDoes an outage break a learning habit, or only pause it?
Write itGamified learning that punishes you for its own outage.
Reported repeatedly
Duolingo
Duo now forces users to use AI
Build itEvery interruption carries a close control, and it is tested.
Start itNot a company. This is a policy question, not a product gap.
Study itDoes an undismissable prompt change lesson completion?
Write itLearning interrupted by the thing that sells you learning.
Reported repeatedly
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