After WordPress 5.9, a new language selection has been added to the default login page in the background. It was originally thought to be used to select the site language when multiple users log in. After trying, it was found that only changing the display language of the login page is equivalent to translating the web page. I don't know whether this function has other uses.
You can use the filter provided by WordPress to remove this function.
Add code to the current topic function template functions.php:
add_filter( 'login_display_language_dropdown', '__return_false' );
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