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What is the benefit of splitting login screens into two steps for email and password separately?
Drawbacks I see: 1) I often confuse the first screen for email with a signup form. 2) It's one more click to complete the login 3) It confuses password managers
This stackexchange answer offers some security reasons, but even the author isn't convinced of its use:
https://security.stackexchange.com/a/85180