i've heard that the film starts immediately after the blip, and that is how they explain T'Challa's death. Shuri was presumed blipped because she was rendered unconscious from the battle between Vision and Corvus. When Shuri is found alive she turns her focus to trying to regrow the heart shaped herb. It is during the gap between Avengers Infinity War and Endgame does the crux of this story take place.
After Namor's attack on Wakanda, Shuri develops the technology to enter the ancestral plane. It is there that Shuri discovers that T'challa is not dead. She meets N'dajaka who tells her that T'Chala isn't there, therefore technically not dead. He also shows her where she can find the herb. N'dajaka didnt destroy all of it.
The end of the movie finds the characters realizing that those who were blipped start reappearing.............
…. Yeah mustache
