Add spaces to CF7 field names

hello,i have this code to replace “_” with “” in field names, but not work

function filter_add_spaces_to_field_names($formData) {
    foreach ($formData->posted_data as $key => $value) {
        $key2 = str_replace('_', ' ', $key);
        if ($key != $key2) {
            unset($formData->posted_data[$key]);
            $formData->posted_data[$key2] = $value;
        }
    }
    return $formData;
}
add_filter('cfdb_form_data', 'filter_add_spaces_to_field_names');