Observed behaviour
When adding a new account via Manage accounts on a self-hosted instance whose Sign-in Method is restricted to Username only, the “Create an account” form still behaves as if email-based sign-in were enabled:
The Email field is shown (and appears to be required).
The Username field is labeled (optional) with the placeholder “Leave blank for a random username”.
Reproduction steps
Set up a self-hosted Fluxer instance.
Configure the instance so that the only enabled Sign-in Method is Username.
In the client, open Manage accounts → add/register a new account.
Observe the “Create an account” form.
Platform
Self-hosting