Comment by josalhor

This is a well-understood feature. Facebook does the same thing[0]. Quote:

Facebook actually accepts three forms of your password:

* Your original password.

* Your original password with the first letter capitalized. This is only for mobile devices, which sometimes capitalize the first character of a word.

* Your original password with the case reversed, for those with a caps lock key on.

[0]: https://www.zdnet.com/article/facebook-passwords-are-not-cas...