im aware of how this is going to sound but i knowww the barbie movie is about to push us deeper into the "anything a woman does is her free-thinking choice, so if she wants to wear tons of makeup and shave and be consumable and uphold patriarchal gender norms, that's her decision so it's feminism!" and like don't get me wrong i actually want to see the barbie movie but i can't go through another internet "bimbo feminist" phase. sorry !
there may have been a miscommunication here. The OP is specifically talking about choice feminism, which is the idea that any choice a woman makes is an inherently feminist one just because she is a woman. In reality, while women's freedom to make choices is an important feminist issue, women can make antifeminist choices - for instance, support a political campaign for taking away women's rights.
This is relevant to Barbie because of the idea of womanhood she represents. Pink, glittery, wearing makeup and putting on high heels to shop at the mall. This is a kind of womanhood that young girls are encouraged to identify with through Barbie, and it is one that is beneficial to capitalism. Fashion, makeup, skincare routines, razors - have you ever seen a Barbie with body hair?
The Barbie movie is a commercial for Barbie toys, but Barbie as a cultural figure is also a commercial for this version of womanhood. One that is supported by society as a whole. Women are pushed to wear makeup, to dress feminine, to be invested in fashion and obsess over their appearance and remove all perceived flaws even when they're just completely harmless, natural features (see again, body hair).
None of that is to say that women shouldn't do those things, but it is important to be aware of that social pressure and the way it affects our decisions. By wholly embracing Barbie as a feminist icon, we risk losing sight of that, and recreating that same societal pressure within feminism.