What potential issues can arise when using the code to extract the current URL in PHP?

One potential issue that can arise when using code to extract the current URL in PHP is that it may not always return the correct URL, especially if the script is running on a server with a proxy or load balancer. To ensure the correct URL is retrieved, you can use the `$_SERVER['REQUEST_URI']` variable instead of relying solely on `$_SERVER['HTTP_HOST']` or `$_SERVER['PHP_SELF']`.

$currentUrl = "http://$_SERVER[HTTP_HOST]$_SERVER[REQUEST_URI]";
echo $currentUrl;