Set email address used for Stripe modal form using url parameter

ds-filter-params.php

<?php
/*
* The 'ds_filter_params' filter hook will be available from Direct Stripe 2.1.8
*/
add_filter( 'ds_filter_params', function( $params ){
    $email = $_GET['email']; //url parameter set as ?email=user@domain.ext
    if( isset($email) ){
        $params['current_email_address'] = $email;
    }
    return $params;
} );