MC-17808: Custom customer attribute code showing on guest checkout

Author: Oleksandr Iegorov

app/code/Magento/Checkout/view/frontend/web/template/billing-address/details.html

@@ -23,6 +23,9 @@
                 </if>
             </ifnot>
         </if>
+        <if args="typeof element === 'string'">
+            <text args="element"/>
+        </if><br/>
     </each>
 
     <button visible="!isAddressSameAsShipping()"