This has been disabled by default for privacy reasons. Most people trying to save recipes from Safari should switch to the Safari extension instead, as described here:
https://www.paprikaapp.com/help/ios/#shareextension
If you really want to turn it back on, you can do so under Paprika's Settings -> Browser -> Detect Clipboard URLs.
Note for iOS 16 (and later)
If you do turn it on, you probably also want to change iOS Settings -> Paprika 3 -> Paste from Other Apps to Allow, otherwise you will get an annoying privacy prompt every time Paprika tries to read the URL off the clipboard.