Update: Editing your review works fine, thanks. Yes, I'm on a Mac. What version of Firefox and our extension are you running, please? (I was able to save your Etsy listing just now.) Are you switching Pinterest accounts, by any chance? If so, please try restarting Firefox.
If you are getting the same error from the Pinterest back end when you try to save using Artfire's button, it's not a problem we can fix with the browser extension. Can you please give me an URL or two to test? I was just able to successfully save from here: https://www.artfire.com/ext/shop/product_view/14691496