Get the value of a Buckaroo parameter on payment status changes with the Pronamic Pay plugin for WordPress.

pronamic-pay-buckaroo-use-brq-parameter.php

<?php
// Add below code to functions.php of your WordPress theme.

/**
 * Pronamic Pay status update process Buckaroo parameter.
 *
 * @param Payment $payment      The payment.
 * @param bool    $can_redirect Whether or not to redirect.
 * @param string  $old_status   Old paymet status.
 * @param string  $new_status   New payment status.
 */
function pronamic_pay_status_update_brq_param( $payment, $can_redirect, $old_status, $new_status ) {
	$method = filter_var( INPUT_SERVER, 'REQUEST_METHOD', FILTER_SANITIZE_STRING );

	$data = ( 'POST' === $method ? $_POST : $_GET );

	// Process brq_transactions parameter.
	if ( isset( $data['brq_transactions'] ) && ! empty( $data['brq_transactions'] ) ) {
		$brq_transactions = $data['brq_transactions'];

		// Your custom code with $brq_transactions here...
	}
}

add_action( 'pronamic_payment_status_update', 'pronamic_pay_status_update_brq_param', 10, 4 );