Prevent WordPress from convert ✔ (& other text symbols/emoji) to SVG

The code from this page solved the problem for me.

/**
 * Disable the emoji's
 */
function disable_emojis() {
 remove_action( 'wp_head', 'print_emoji_detection_script', 7 );
 remove_action( 'admin_print_scripts', 'print_emoji_detection_script' );
 remove_action( 'wp_print_styles', 'print_emoji_styles' );
 remove_action( 'admin_print_styles', 'print_emoji_styles' ); 
 remove_filter( 'the_content_feed', 'wp_staticize_emoji' );
 remove_filter( 'comment_text_rss', 'wp_staticize_emoji' ); 
 remove_filter( 'wp_mail', 'wp_staticize_emoji_for_email' );
 add_filter( 'tiny_mce_plugins', 'disable_emojis_tinymce' );
 add_filter( 'wp_resource_hints', 'disable_emojis_remove_dns_prefetch', 10, 2 );
}
add_action( 'init', 'disable_emojis' );
/**
 * Filter function used to remove the tinymce emoji plugin.
 * 
 * @param array $plugins 
 * @return array Difference betwen the two arrays
 */
function disable_emojis_tinymce( $plugins ) {
 if ( is_array( $plugins ) ) {
 return array_diff( $plugins, array( 'wpemoji' ) );
 } else {
 return array();
 }
}
/**
 * Remove Emoji in WordPress automatically CDN hostname from DNS prefetching hints.
 *
 * @param array $urls URLs to print for resource hints.
 * @param string $relation_type The relation type the URLs are printed for.
 * @return array Difference betwen the two arrays.
 */
function disable_emojis_remove_dns_prefetch( $urls, $relation_type ) {
 if ( 'dns-prefetch' == $relation_type ) {
 /** This filter is documented in wp-includes/formatting.php */
 $emoji_svg_url = apply_filters( 'emoji_svg_url', 'https://s.w.org/images/core/emoji/2/svg/' );
$urls = array_diff( $urls, array( $emoji_svg_url ) );
 }
return $urls;
}