Doing a lot of thinking about Shang-Chi and the thing I'm thinking about most is, why would the Chinese population in Asian countries (mainly speaking about those in Mainland China, since that's where I hear most of the criticism from, though I've also heard people from HK, TW, and other countries also having issues) be so adverse to this movie, yet the Chinese population who live in other countries, especially the Chinese population in Western countries, seem to love the movie or at least appreciate what it means to them culturally?
And I think it's just that: there's a huge cultural disconnect between the Chinese Diaspora population and the Chinese people who live in Asia.
Let's break some of the issues they have with the movie down (warning: movie spoilers ahead):
The main villain of the movie comes from an offensive stereotype against the Chinese - while the original Mandarin or Fu Manchu characters in the comic books are definitely incredibly offensive, Xu Wenwu is basically a completely different character who only shares a title with the Mandarin character from the comics. Disney and Marvel made sure that Xu Wenwu was a multifaceted, complex character who was not a negative racial stereotype. I'm certain anyone who continues to make this argument now either never saw the movie or is just trying to stir up stuff that doesn't actually exist in the context of the movie.
Simu Liu and Awkwafina are ugly, especially if they're supposed to portray the main characters of the film - beauty is incredibly subjective and differs from culture to culture. Simu's features may be attractive in the west (broad shoulders, cut abs, square jawline, slightly tanned, boyish smile), but to those in China, his features are less than desirable (the ideal guy has a more angular face and softer facial features, thinner frame, paler skin, and more stoic expression/less emotive in general). Awkwafina suffers from similar traits: round faced, tanned skin, fuller lips, and a very husky alto voice, when the ideal woman in China would be thinner cheekbones, pale skin, smaller lips, and a higher-pitched, clear girlish voice.
The movie is too Westernized and doesn't accurately portray Chinese culture - it's flat out just not supposed to. Maybe Ta Lo should be more similar to Historical China, but even then Ta Lo is more of a fantastical place with features inspired from Chinese myths and legends. The other stuff? Straight out of what many Chinese Americans experience every day. Many of the people involved with the story, including the directors, writers, and actors, took inspiration from their own lives to create the story and the background for what the characters go through. The film's culture is not supposed to be Chinese culture as you would see it in China, or Hong Kong, or Taiwan, it's a reflection of Chinese American culture, which is related to but still separate from Chinese culture as experienced in those countries.
The movie's themes are antithetical to Chinese values - This one is tricky. Family and respect are both themes that resonate strongly with Chinese culture, and this film plays heavily into exploring what exactly that means to our characters, both for our protagonists (Shang-Chi, Katy, and Xialing) and our antagonists (Wenwu). But the beauty of this movie is showing the struggle all of them face in reconciling their views and experiences about "family" within themselves, and with each other. The Xu family were all very close until the mother, Ying Li, passed away, a tragedy which tore the family apart. Wenwu harshly trained his son to the point of emotional and physical abuse, while neglecting his daughter, making both of his children distance themselves from him for how he treated them. Shang-Chi and Xialing, however, also have a rocky relationship in the beginning, thanks to Shang-Chi abandoning his sister despite promising to come back for her. Wenwu and Shang-Chi constantly butt heads throughout the movie. But in the end, the siblings make up with each other and support each other, and father and son realize that though they've hurt each other so much, they still love and care about each other and dont actually want to cause more pain, they just dont know how else to reach the other. And is that not how so many families are? A little broken, not perfect, maybe everyone hurting, but in the end you're still trying to do what you can for each other? If that isn't respecting the value of family, then... well, I'm glad you probably have a healthier family life than I did, or many of the people I know did.
TL;DR Chinese people are judging this movie before they even watch it. And if they watch it and still come to these conclusions, well, this movie isn't for you. It's for us, the ABCs you've forgotten about, the bananas you chose to throw out because we weren't authentic enough for you. This is our movie, and sometimes, not everything is about you. But for once, it is about us.