Okay, please use the following code:
add_filter("wdm_before_fetch_template", function ($vars, $template, $type) {
$vars['package_size'] = explode(" ", $vars['package_size']);
$vars['package_size'][0] = (int)$vars['package_size'][0];
$vars['file_size'] = $vars['package_size'] = implode(" ", $vars['package_size']);
return $vars;
}, 10, 3);
