Asian writers have said that these confused people were white and that their confusion is an indication of not understanding Asian culture. Although symbolism and the telling of history differs from culture to culture, some people just don't pick up on symbolism or certain story elements as well as others do. Another (white) person, who grew up with an overprotective mother, called the confused viewers "racist fucks".
Food has different meanings and different forms across different borders as well, but a family meal generally means love, stability, and unity. As someone who loves cooking and grew up with a lot of food-centric family events, I picked up on the symbolism rather easily. However, I understand that may not be the case for everyone. If you came from a background where you had to grab your food and go or where food was prepared with little thought, I can see where the symbolism might have been confusing.
I think the film would have been equally confusing to these people had it featured a Russian woman and a pirozhki or a black woman with fresh, hot biscuits. Either way, the confusion is way more likely to do with one's way of thinking or relationship with food than race. Director Domee Shi wanted to make something shocking and "creepy-cute" and shocking she did with this animated short whether you got the symbolism or not.
Sources and Photos (DOA 6/3/18):
https://www.indy100.com/article/pizar-short-bao-incredibles-2-white-people-confused-asia-china-8425586
https://www.inverse.com/article/46388-pixar-bao-dumpling-short-audience-confusion-asian-families
https://www.thrillist.com/entertainment/nation/bao-pixar-short-film-before-incredibles-2-explained
