What’s going on?
It turns out that Google starts a new session anytime someone comes to your site from another site. If we think about this flow when you have PayPal enabled as a payment solution in Shopify (or any other ecommerce platform for that matter), it makes sense. A user comes to your store, adds something to the cart, then goes to checkout with PayPal. They’re redirected to PayPal.com to complete their transaction, and then they come back to your site.
Because someone came to your site from another site (paypal.com in this case), Google Analytics counts it as a new session. This means that PayPal gets credit as the referral for the transaction because it was the last site someone visited before coming to your site and completing a transaction.
How to Fix:
To ensure that domains you don’t want attributed as referrals are excluded:
1. In your Google Analytics Admin, click on your Tracking Info.
2. Make sure you have the following domains in your Referral Exclusion List:
- yourwebsite.com (the primary domain of your site, you may have more than one)
- checkout.shopify.com (if you're using Shopify)
- paypal.com (if you’re using PayPal)
- any other external payment gateways you are using.