What can replace a function in smarty?

Question

Smarty

There is such a function in the template that pulls up the pop-up window of the product

{* QUICK VIEW *}
{if $smarty.server.HTTP_X_REQUESTED_WITH|strtolower == 'xmlhttprequest'}
    {$wrapper='quickview.tpl' scope=parent}
{/if}

After the update it stopped working.

[23-Jul-2021 13:47:35 Europe/Moscow] PHP Fatal error: Uncaught --> Smarty Compiler: Syntax error in template "/home/public_html/design/okay_shop/html/product.tpl" on line 8 " {if $smarty.server.HTTP_X_REQUESTED_WITH|strtolower == 'xmlhttprequest'}" modifier 'strtolower' not allowed by security setting <--
thrown in /home/n/nconcuj9/prof-techno.bestintop.ru/public_html/vendor/ smarty/smarty/libs/sysplugins/smarty_internal_templatecompilerbase.php on line 8

Writes what was removed because of security, but what can now be used by analogy?