For some users Anti-Spam by Clean Talk will block the submission of payment forms and display the following error,
Cannot read properties of undefined (reading "id")
To resolve this, you will need to whitelist the WP Simple Pay requests in the CleanTalk settings by marking them as “Not Spam”: https://cleantalk.org/help/feedback-spam
Requests to the WP Simple Pay REST API endpoints should also be unblocked and formatted as shown below:
Once the above is complete, activate the WP Simple Pay reCAPTCHA settings which can then run on those endpoints to provide spam protection for your payment forms instead of Anti-Spam by CleanTalk.