While Proton Pass is great for generating alias emails, it lacks an essential feature: a dedicated "username" field. Many websites require both an email and a username during registration, and often, these sites only accept the username login. This creates a frustrating experience in its automatic fill-in process.

to improve usability, Proton Pass should offer a feature that allows users to choose between filling in their email or username in auto-fill pop-ups. This would be especially useful for cases where the user sets up their login with both a username and an email, ensuring the correct credentials is used based on the website's login requirements.