GitHub authentication failing over https, returning wrong email address

Question

Initiating a push or any other action with GitHub from the command line (over https, not ssh) that calls for the username and password not only fails but, when it does, it r

Answer 1

I do not have an @github.com address

You don't have to: the @ is the separator between the username:password and the domain.
It is not an email address.

A full GitHub https url would be:

https://username:password@github.com/username/reponame.git

Without the password (which would then be asked on the command line), that would gave:

https://username@github.com/username/reponame.git

But again, username@github.com isn't an email address, just the first part of the credentials.

Make sure the case of your username and reponame is correct: it is case sensitive.

Note that you can store and encrypt your credentials in a .netrc.gpg (or _netrc.gpg on Windows) if you don't want to put said credentials in clear in the url.
See "Is there a way to skip password typing when using https://github".