https://www.cnet.com/news/avengers-endgame-new-trailer-captain-marvel-and-thor-first-meeting-danai-gurira-poster/

The trailer opens with a stranded-in-space Tony Stark (Robert Downey Jr.) recording a message for his Earth-bound fiancee Pepper Potts, reminiscing about his first days as Iron Man and falling in love with her. (But still no sign of Pepper in the current timeline, however.)

It kicks off a series of mostly black-and-white flashbacks to the various Avengers' past adventures -- like Steve Rogers' pre-Captain America World War 2 life and the now destroyed Asgard -- and the Snappening by Thanos in Avengers: Infinity War. Fascinatingly, the only color we see in these parts is red (like the beginning of the first Endgame trailer).