Quite a few people use the word "login" as a synonym for a username. Often you can find a form to enter the site with the fields "login" and "password". But this is wrong, wrong and incorrect. Login is a procedure for user authentication in the system. In most cases, it consists of specifying a username (or e-mail address) and a password.
When and where the incorrect use of the word “login” came from, I do not know, I didn’t get to the bottom. But nevertheless, the situation must be corrected. :-)