In iPadOS and iOS 13, long-pressing a link does two things simultaneously. It brings up a contextual menu with options for sharing and so on, and it loads a preview of the linked web page. Apple calls this a link preview.
But what if you don’t want a link preview? Maybe you’re on a cellular connection and you don’t want to waste data by loading pages you won’t read. Or maybe you only need the link, and never want to see the page. What if it’s a link to a huge image, or an MP3? Or perhaps it’s a link in an email, and you want to use the contextual menu to check the URL for scams. In this last case, there’s no way you want that link to load. It could prove disastrous.
The good news is that you can disable link previews in iOS 13 with a single tap.