Elias here with Shopify Support. Thank you for reaching out.
Typically, unless there's missing information during checkout or the checkout is being directed to externally (eg. PayPal, third-party payments), there isn't a review order message. However, so that we can have a better idea of what might be happening - Is this something you can replicate in your checkout? Or, is it possible to get some screenshots from your customer?
If there's any sensitive information on the screenshots, please crop or black out that information and I'd be happy to take a closer look!