I'm not sure that type of hyperlink button is actually covered by the patent. I'm not an expert, but it seemed to indicate 2-way communication, such as the direct IAP provides.
But the hyperlink button is indeed one of the things they are sending out letters for. Very clearly stated by the developer:
"...We were told that the button that users click on to upgrade the app, or rather link to the full version on the app store was in breach of US patent no 7222078, we couldn't believe it, the upgrade button!?!"
https://www.macrumors.com/2011/05/1...sue-app-store-developers-over-purchase-links/