Does this affect transactions conducted directly through Paypal’s site?
“...mathematically proves login pages aren’t forgeries that were set up by con artists who are sitting in between the user and the website he’s trying to view.”
Yes. It affects all web pages in the secure portion of the site.
If you are the one putting in the “www.paypal.com” into your browser, you’re fine.
This affects the “pay with PayPal” buttons on a merchant’s website that can steer you to a phony PayPal screen that fools your browser into thinking it’s legit.