Change the logo and url on the login page

functions.php

// Update the login logo with the custom header image
function custom_login_logo() {
    // Get the header image from the Customizer
    $header_image = get_header_image();

    if (!$header_image) {
        return;
    }

    // Styles to replace the WordPress logo with the custom header image
    $custom_css = sprintf(
        '.login h1 a {
            background-image: url(%s);
            background-size: contain;
            width: 100%%;
            height: 120px;
            display: block;
            margin-bottom: 10px;
        }',
        esc_url($header_image)
    );

    echo '<style type="text/css">' . $custom_css . '</style>';
}

add_action('login_head', 'custom_login_logo');

// Change the URL of the login logo to the site's homepage
function custom_login_logo_url() {
    return home_url();
}

add_filter('login_headerurl', 'custom_login_logo_url');

// Change the title attribute of the login logo link
function custom_login_logo_url_title() {
    return get_bloginfo('name', 'display');
}

add_filter('login_headertext', 'custom_login_logo_url_title');

If you're using a theme that registers a new custom logo area, you can use that function to get it:

https://developer.wordpress.org/themes/functionality/custom-logo/#displaying-the-custom-logo-in-your-theme

`function custom_login_logo() {
// Get logo
if ( has_custom_logo() ) {
$custom_logo_id = get_theme_mod( 'custom_logo' );
$header_image = wp_get_attachment_image_src( $custom_logo_id , 'full' );
$logo = $header_image[0];
} else {
$logo = get_header_image();
}

if (!$logo) {
    return;
}

// Styles to replace the WordPress logo with the custom header image
$custom_css =
    '.login h1 a {
        background-image: url('. esc_url($logo) .');
        background-size: contain;
        width: 100%;
        height: 120px;
        display: block;
        margin-bottom: 10px;
    }';

echo '<style type="text/css">' . $custom_css . '</style>';

}`

Thank you and thank you for commenting here too!