I’ve read and watched enough reviews on Mulan and I think I know what pissed off Chinese audiences.
If you want to strip away the songs and animal sidekicks and sell the movie as an epic period piece, you better go all out with the seriousness of a period piece. People are expecting something like the Gladiator or Kingdom of Heaven, and Disney gave them a mash of The Great Wall and the Mummy: Tomb of the Dragon Emperor.
Mulan being born with super natural qi is plain stupid. In all good Wuxia stories, Qi is something that one needs to work for. Even if one is suddenly imbued with Qi, it usually requires performing selfless acts, otherwise it would come with consequences.
Giving Mulan super human powers at birth diminishes the sacrifice she made to save her father from serving. Her father also looks way too young in the movie.
If they had to turn it into a Wuxia moving, then they should at least delay Mulan receiving qi powers until after her first defeat against the Rouran.
Anyway, this whole movie looked ridiculous the moment Mulan showed up in a Tulou, which appeared much later than the story of Mulan.