This episode introduces Impulse. In this story, like Nora, he is the future child of Barry and Iris. This makes them brother and sister. In the original comic books they are cousins, the grandchildren of Barry and Iris.
It's established that this Nora is different to the one from Season 5. Notably, this one had a happy childhood and is a lot more happy and responsible as a result.
Nora saying that she's nearly thirty and Barry and Iris giving her a skeptical look in response is a reference to the fact that Jessica Parker Kennedy, the actress who plays Nora, was nearly thirty-seven at the time. In actual fact she is older than both actors who play her parents.
This episode marks the return of Jay Garrick/The Flash who last appeared in A Flash of the Lightning (2019).
Whether it's because of the Legends changing the timeline, because of Crisis, or because of the changes made to the timeline in Legacy (2019), the future has been changed drastically since Nora last appeared in the present day. Barry is alive and well, Nora has a brother, and ARGUS is no longer detaining metas simply for existing, allowing Barry's kids to be superheroes out in the open.