In Bug 1708455, we support multi-page login form for username fields with an associated form. But there are cases where username fields in the login page doesn't have an associated form. For those fields, our password manager doesn't treat them as username fields, so password manager logic doesn't apply.

Currently we don't support the use case because we don't want to run our heuristics on every eligible <input> field, which might introduce performance overhead if we don't do it carefully. However, this is still something we can support if we find the right approach to do it.

Still happening on Twitter.

Original bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1745105