This website uses a security service to protect against malicious bots.

that's a point, but I would say the opposite, when entering credit card data I would rathre prefer to be entirely in the Verified By Visa (Paypal) webpage (with the url easily visible in the address bar) rather that entring my credit card data in an iframe of someone's website.

IFRAME element may be a security risk if any page on your site contains an XSS vulnerability which can be exploited

While stylesheets can be reworked relatively easily with AMP by inlining the CSS, the same is not true for JavaScript. The tag 'script' is disallowed except in specific forms. In general, scripts in AMP are only allowed if they follow two major requirements: All JavaScript must be asynchronous (i.e., include the async attribute in the script tag). The JavaScript is for the AMP library and for any AMP components on the page. This effectively rules out the use of all user-generated/third-party JavaScript in AMP except as noted below.

It is important to note that the path attribute does not protect against unauthorized reading of the cookie from a different path. It can be easily bypassed using the DOM, for example by creating a hidden iframe element with the path of the cookie, then accessing this iframe's contentDocument.cookie property. The only way to protect the cookie is by using a different domain or subdomain, due to the same origin policy.