You are working with an event registration form 2.0 or payment 2.0 part which proceeds to the secure payment page. When inputting a transaction, you may notice the page displays cached content/an incorrect design. If you create a new form on the site and proceed to the payment page, you may notice the generic secure payment page is displayed.
When HTML Comments are in the Style Sheets, this may happen. Remove the HTML Comments from the CSS Style Sheet.
We are currently evaluating this issue and will update this article when we have more information.
Steps to Duplicate
Create a new page with an event registration form 2.0.
Navigate to Administration > Sites & Settings > Schedules.
Update the secure payment templates.
Submit a test transaction through the new event page.
Observe the generic secure payment page is displayed.