Yeah the Earth 616 timeline was destroyed - we see it fading away at the end of Endgame after old Steve Rogers returns. The new timeline is Earth 616b, an alternate timeline where Thanos, disappears during the war for New York, meaning he never snaps.
Essentially, everyone that they saved (who died from the snap) came back for five minutes and then doesn’t exist anymore, as well as anyone who survived.
Also, there is a 3rd timeline in which Loki steals the tesseract.