In EZ Exporter, you can use a Calculated Field with a formula like below to strip out the query string portion of the URL data (the part after the question mark):

strip_url_query_string({{ referring_site }})

So if the value of the referring_site field from the Shopify order data looks something like:

https://www.somecoolblog.com?ref=coolblog&medium=email&campaign=1132%20featured

The formula will strip out everythign after the "?" symbol and simply return this:

https://www.somecoolblog.com