No offer to access vault on iOS (Safari) when username and password are on separate pages

I found a really annoying break in the iOS user experience. It may or may not be caused by Bitwarden.

The problem manifests when attempting to log on to sites where the the first page in the login process is displaying the username only. The vault is only available where a password field is present. So it seems as one only have the option to step aside to fetch the username in the Bitwarden app and paste it on the site.
An example:

This has become a real problem for me as I’m more often are using proxy emails as usernames instead of my default email address.

Does anyone know if a fix can be developed in Bitwarden, or does this how credentials are handled in iOS?