Password field, until username is input' pattern is horrible
You know, the UX pattern where you first have to input the username and only then the password field appears. Forces me to auto fill with Bitwarden twice. Who came up with this? It's so bad.
I think the main reason for that is that you can then offer different authentication methods depending on what works for you and what kind you prefer. If the provider only offers passwords, than this is neglectable. But if you also use SSO, social logins, magic links or passkeys, then it makes sense to tailor the UX to your account.
Also having to click "edit" on the username makes it very annoying. Auth0 implements that.