> When you have a confirmation field, like signups that require you to type your email and then verify your email, blocking paste stops the user from typing a typo and then copy-pasting the typo into the confirmation field.
This argument is indefensible. Browsers have had autocomplete for over a decade, Contact book applications that store email addresses have existed over a decade, password managers that also handle email addresses over a decade.
To be clear, I'm not saying I agree with it. But this isn't a feature for users that have password managers. It's a feature for the staff that handle dozens of calls per week from users complaining they never got the signup email when they had given the wrong email. There's better solutions to that problem though, and like I said I'd be the first to advocate for one. But I can see how it's an easy tool to reach for.
This argument is indefensible. Browsers have had autocomplete for over a decade, Contact book applications that store email addresses have existed over a decade, password managers that also handle email addresses over a decade.