Number to string conversion occured in <?php http_build_query() ?> is affected by locale settings, which might not be obvious.
<?php
$params = ["v" => 5.63];
setlocale(LC_ALL, 'us_En');
http_build_query($params) // v=5.63
setlocale(LC_ALL, 'ru_RU');
http_build_query($params) // v=5,63 mind the comma
?>