I've filled this form and I've got the 'Thank you' confirmation page.
Then each time when I'm revisiting the form, all the old form data is still there. So clicking 'Talk to an expert' each time submits the same data over and over again.
I also don't see the logout button (at
/advertise/create-a-custom-campaign) and on the main page I can only see the Login button which indicates I'm not login, despite the personal data is populated through cookies.
As for workaround, removing all the cookies (such as
UPDATE as per @Patrick answer:
There is no sensitive data exposed, so please keep it like this.
There is actually sensitive data exposed, since this happens when you are not logged in and this data is not associated with any SO account.
Imagine you're going to internet cafe to fill this form and you send all your details for your custom campaign for your business (including some estimated financial details), and you leave after seeing Thank you page, and now all your sensitive data are exposed to anybody who ever goes to business.stackoverflow.com on the same PC (not only at
advertise/create-a-custom-campaign, but on the homepage as well including your e-mail address) as shown below (this happens for any non-logged user and you don't have to have account at all to share your personal details):
So I believe this is a bug (not a feature).
I understand keeping the data may be useful for convenience, but in my opinion not after form submission, especially loading the old description field over and over again without possibility removing it (not everybody knows how to clear the cookies).