What potential issues can arise when using special characters like & and = in PHP URLs?

Special characters like & and = can cause issues in PHP URLs because they are reserved characters used for query strings. To prevent conflicts, these special characters should be properly encoded using urlencode() or rawurlencode() before being included in the URL.

$url = 'https://example.com/page.php?param1=' . urlencode($param1) . '&param2=' . urlencode($param2);