Remove the leading "woocommerce_" from the Woo REST API payment_method attribute

shorten-woo-rest-api-order-payment-method.php

<?php
add_filter( 'woocommerce_rest_prepare_shop_order_object', function( $response ) {
	
	// strip leading woocommerce_ from payment method
	if ( ! empty( $response->data['payment_method'] ) ) {
		
		$response->data['payment_method'] = str_replace( 'woocommerce_first_data_', '', $response->data['payment_method'] );	
	}
	
	return $response;
}, 1 );