Hi @squeaky
It does seem like these could potentially be fraudulent attempts. Fraudsters often use stolen credit cards to perform test transactions, typically with low-cost items. They also tend to use randomly generated email addresses and place orders as guests to avoid detection.
Adding a reCAPTCHA to your checkout page was a smart move, as it can help prevent bots from placing these types of orders. You might also need to consider implementing additional fraud prevention measures. For instance, you can use a fraud detection plugin like WooCommerce Anti-Fraud that can help identify and block suspicious transactions based on various factors.
If you continue to see a high number of failed transactions, I would recommend reaching out to your payment gateway provider. They may be able to provide additional insights or tools to help combat this issue.
I hope this clarifies your concern. If you have any other questions, feel free to ask.