I’m also facing the same issue,
“My problem is, though, if they reload the page, they get this message “confirm form resubmission” which is really annoying.
Also, if not reloading, but every time I come to the page, it still has the message that you’ve already signed up. I would prefer that doesn’t show up every time they come to the page. Is that stored in a cookie or something that I need to delete? I don’t like that message always being there because it kind of clutters up the page.”
Here is the link
https://dmritesh.com