Issue with Webhooks by Zapier Post action when file object is included

Hi!

I've encountered an issue when using Webhook (POST). When I include a file object and Data in the POST request, the data Data options get formatted as a single string, like this:
Array ( (data] => client_id=3&order_number=12345 )

However, when I don't include a file object, the data field options are sent separately, which is the desired format:
Array ( (client_id] => 3 3order_number] => 12345 )

I want my data fields get passed in this way even after including a File object

Is there a way to send the data field options separately even when I POST a file object together?

FYI,
My API is developed using PHP and used print_r($_POST); to check how the data fields get passed to my API