The scraped data of 2.6 million DuoLingo users was leaked on a hacking forum, allowing threat actors to conduct targeted phishing attacks using the exposed information.
They know your email, your name, and that you've taken German anf Japanese. Next they use that information to craft a phishing email that only the very stupid would fall for, which fools an alarming number of people. Something like "Hi, this is Duolingo suppert, and your billing information may have been comprimised. Log into this portal with your credit card credentials to confirm that you were not affected."