Fixing Google Docs formatting

strip-google-docs-formatting.php

<?php
add_filter( 'wp_kses_allowed_html', function( $allowed_tags, $context ) {
    if ( isset( $allowed_tags['span'] ) ) {
        unset( $allowed_tags['span'] );
    }
    foreach ( $allowed_tags as $tag => $attrs ) {
        $allowed_tags[ $tag ]['style'] = false;
        $allowed_tags[ $tag ]['dir'] = false;
    }
    return $allowed_tags;
}, 10, 2 );