John Wilander, Webkit Blog:
Cookies for cross-site resources are now blocked by default across the board. This is a significant improvement for privacy since it removes any sense of exceptions or “a little bit of cross-site tracking is allowed.”
Safari continues to pave the way for privacy on the web, this time as the first mainstream browser to fully block third-party cookies by default. As far as we know, only the Tor Browser has featured full third-party cookie blocking by default before Safari…
Starting in Safari 13.1 for Mac and iOS 13.4, there are some additional changes to Intelligent Tracking Prevention. Information a website stores in local storage will now be erased if you don’t visit that website at least once every 7 days. This affects full-featured web apps like 1Password that use local storage for legitimate purposes. For example, 1Password stores your Secret Key in local storage. If your Secret Key is removed from Safari and you don’t have it stored anywhere else, you won’t be able to access your account.