Prevent Users from Entering E-mails during Registration

Describe the feature

A small minority of users mistake the "Username" field for a place to enter their e-mail address. As for why this is the case, I don't have an explanation, but I believe a barrier should be put in place to prevent new users from needlessly giving up a piece of personal information.

Note: If any users reading this have entered their e-mail on any Piped instance, you have the ability to delete your account and make a new one (Preferably with a non-identifying username), assuming it's up-to-date. Subscriptions can be exported before account deletion if needed, but playlists cannot.

Why would this be useful to add?

This would add a layer of protection for users discovering Piped (perhaps new to FOSS alternative frontends) to ensure they don't give their e-mail to a service that never asks for it.

Concept(s)

Maybe a filter for the "@" character, with a message saying "Piped does not require an e-mail address for registration!" would be sufficient?

Additional context

No response

Acknowledgements

[X] I have searched the existing issues and this is NOT a duplicate or related to another open issue.
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TeamPiped / Piped