Rick Curran

WordPress 5.9 added a new language selector to allow users to switch languages from a dropdown on the login screen if more than one language is enabled on your WordPress installation. This plugin provides a quick and easy way to prevent this language selector from appearing.
It is a very simple plugin which is provided for ease of use: you need only to install and activate the plugin and it will prevent the language dropdown from appearing on the login screen of your site.
Alternatively, you can also achieve the same effect by adding the following line of code to the <code>functions.php</code> file in your theme:
<pre><code>add_filter( 'login_display_language_dropdown', '__return_false' );
</code></pre>

Disable Login Language Selector

Remove the language selector from the login screen if you have more than one language enabled in WordPress 5.9 and later.

Disable Login Language Selector vs Autoglot – Automatic WordPress Translation