rpress_payment_customer_id

This filter is applied to use the payment customer ID, it is including two parameters.
$customer_id -> get the int value of customer-id
$ID -> is used to get id.

An example of how you can append additional information:

function get_customer_id( $customer ){
// its return customer id.
return $customer;
}
add_filter( 'rpress_payment_customer_id', 'get_customer_id',10,2 );