Hey Max, not sure if you are a fellow white dude or not, but if you’re actually curious to know why this is a big deal for her, there are plenty of comments on the article that explain it clearly.
Just to name a few:
There is a history in the US of depicting people of asian descent as evil, buck-toothed, monkey like creatures. A lot of this propaganda was spread during the Japanese internment, but those caricatures persist to this day.
Comic books and movies have portrayed this caricature as well. Showing asian people as inferior, out of place, and too stupid to learn english.
This snapchat filter, represents those very same caricatures. For anyone who possesses those genetic qualities, that caricature is perceived as highly racist.
The moral of the story is, whenever a person of color expresses discontent with something that they feel is very hateful or racist, they probably have a very, very good reason to feel that way. One should not automatically assume they are “playing the race card” to win some internet points. As a white person, it is easy to dismiss these things, because a white person will never, ever be the subject of these racist stereotypes (at least in the USA).