Can we stop that trend of only showing the username field and then show the password field after filling the username clicking next? It messes with my Keepass browser addon.
Apart from that, it messes with human workflow as well. Enter Username -> TAB -> Enter Password -> ENTER. With that stupid UI you have to either focus the next button with Tab and hope hitting Enter does not already submit the login form or switch to mouse and click the Next button.

Im using keepassxc with the addons and that has no problem with multi page logins.

There are different authentication providers for different domains on such pages. Enter example@dell.com on a Microsoft login page.

@stop The KeePassXC add-on also works with regular KeePass with the native messaging plugin.

@sbiewald haven't usdd the normal keepasxc with addons in years.

Even while my password manager actually works fine with that UI flow, it really annoys the hell out of me too.
It doesn't fit the standard scheme of two fields and a button - but matches perfectly one field and a button, which is associated with search...

Calling "login" "sign in" and "register" "sign up" and styling the one you use the most (login) to be less visible than the other one is also making UI mopre annoying to use.

@sbiewald That is a fair point. But would that matter for the task "fetch credentials from the user"? Wouldn't the backend route your data to the correct provider and verify it?

@DBX12 No. In my example, a user log's in with a dell account. Of course Dell does not trust Microsoft with the password of their users.
Additionally, some companies may not even use pawords, but Kerberos, certificates or FIDO2 tokens - 2FA might or might not be required if VPN is used. All of those decisions are happening at Dell's authentication server, not Microsoft's. As a user, I also don't trust a random website with my Google account's.

While Microsoft has all the options (2FA, conditional access, ...) at their side, too, but Dell surely as a dozen systems their users authenticate to with the same policies for all services.

Last, but not least, Dell employees will only login to the Dell login server and only once. When they login to e.g. Microsoft then they will be redirected to the login server but will not be required to enter any password again (single sign-on).

@sbiewald But that would be OAuth ("Login with X") and usually is displayed as a button of the authentication provider, right?

I'm not familiar about logging into Microsoft accounts with Dell so maybe it works that way.

@DBX12 there are multiple methods for this. OAuth is one of two popular methods, the other one is SAML, which also has an feature for logging out.

@DBX12 How many buttons do you want to have?
Each company can register one provider per domain at Microsoft.