I saw it on Expensify yesterday
Doesn't this break a best practice? If you input an email address it tells you whethere there IS or ISN'T a user, and if there IS it asks you for their password.
I thought the best practice was to make it unclear whether an email or username is in the system, which would make this a huge regression
It's useless obfuscation. 99% of systems that tell you "if you entered a valid username, we'll email you a password reset link" also don't allow duplicate accounts by email. Try to register a duplicate on their sign up page and they will tell you "this email address is already in use."
Useless "security" obfuscation and creates a terrible user experience trying to reset passwords.
If the user is confused about their credentials, they'll have to use the "I forgot" system in both cases.