Event Gallery implementes PayPal, Braintree and Stripe as payment methods.
To initiate a payment, Event Gallery submits the email address and the order-id to Stripe. The Stripe-UI in the checkout will include JS/CSS in your website. This includes the transfer of the IP and cookies.
To create a Paypal transaction, Event Gallery needs to transfer the orderid to Paypal. The payment process will redirect your customer to Paypal so they are able to collect user data.
To create a Braintree transaction, no user data is transfered to Braintree. The transaction is handled on your server. The braintree UI will include JS/CSS in your website. This includes the transfer of the IP and cookies.