Avoid login with email account

Hello,

my client has asked me to prevent users from logging in with their email address, being able to do so only through their username.

For this, I have included the following code in the functions.php:

remove_filter (‘authenticate’, ‘wp_authenticate_email_password’, 20);

Only if I deactivate the WP Cerber plugin, I get this code to work, so I understand that there is some configuration in your plugin that must be prevailing.

Any idea what it could be?

Thank you very much in advance.