Primarily these are authentication or payment flows where a top-level site either opens a pop-up window or redirects to a third-party site for an operation and then returns to the top-level site, making use of a cookie either on that return journey or in the embedded context. We intend to provide a temporary set of heuristics to identify these scenarios and allow third-party cookies for a limited amount of time, giving sites a longer window to implement the necessary changes.