polyfill:<?phpif(PHP_VERSION_ID < 80400) {function mb_ucfirst(string $str, string $encoding = null): string{ if ($encoding === null) { $encoding = mb_internal_encoding(); } return mb_strtoupper(mb_substr($str, 0, 1, $encoding), $encoding) . mb_substr($str, 1, null, $encoding);}}?>if you wonder why i bother with mb_internal_encoding: prior to php7, $encoding was not nullable. if your polyfill don't need php5.6 support, you can drop it.