The unfinished scene is set at a burning building. The Hulk jumps down into the street holding a satellite dish, which he uses to carry people away from the fire. After that heroic act, we see him get a phone call, saying, “Steve who?” So that’s apparently meant to be set right before Hulk has his meeting with Steve Rogers and the other Avengers at the diner, where he takes a photo with fans, etc.
Article source: https://www.cinemablend.com/news/2475813/avengers-endgame-re-release-spoilers-heres-exactly-what-was-added