After sending the message, the fields are CLEARED, i.e. the message is NOT PRESENT in the contact form after sending.
If you return to the contact form to send another message, the notification “Thanks your email was sent successfully!” is STILL SHOWING at the top of the form. Refreshing the page does not remove it.
If you start writing another message, the notification remains on the form. If you ignore it and send the new message, there is no way of knowing if the notification was refreshed, so you do not really know what happened.
If you try to delete the “Thanks your email was sent successfully!” notification, the old complete (e-mail) message REAPPEARS on the contact form and can be resent.
There are other issues, but the above should not happen. The design is still broken!