AIKIDO-2026-163472

TL;DR

During guest checkout, the payment address email is matched to an existing customer and, on a match, that customer is set as the context user for the checkout request with no password or ownership check. The order is stored under that customer and the basket delivery addresses are written onto that customer. The account creation option only controls creating a new account when the email does not match. The fix never returns an existing customer's ID from this lookup, so a matching email keeps the order a guest order.