That does seem to be the Discourse of the Month, doesn’t it?
Short answer: no, it is not racist to have a kintype of a race different than your own.
Long answer: A kintype is an integral part of a person, discovered through self- introspection and thought, not something chosen on a whim. The entire “racist to be kin of someone of another race” argument is full of holes. If you believe that kinity is due to reincarnation, are you saying that souls cannot travel between people of different races? Are the souls of a black person and a white person so different?
Let us be clear that, someone who had a past life of a person of another race/gender/ect. shouldn’t be speaking as though they have that experience in this life. At the same time, a kintype is not something that can be “dropped” or otherwise pushed away just because someone on the internet finds it distasteful.
Many kintypes at the center of this discourse are not even human, or would not experience racism in the way a 2016 American does. The Gems of Steven Universe, for example, are aliens who have their own complex caste system. A character living in another country or a different time period probably experiences prejudice in a different way than we do here and now.
There are also plenty of universes with their own forms of racism/prejudice. Where are the people telling Zootopia kin they can’t be Preds if they’re white? (please don’t start doing that)
What I’m saying is that a character’s race is not the end-all be-all of their entire personhood, and it is a ridiculous reason to be going around harassing other people. As some may know, this discourse was originally started by a group pretending to be Japanese girls who wanted to have all the anime kintypes to themselves without having to deal with doubles, so they started going after white people for identifying as anime characters. Unfortunately, since then, it has taken a life of it’s own.
If you are being harassed over this, my best advice is to block and move on. Trying to repress a kintype usually only makes the homesickness/shifts/ feelings stronger and more unpleasant.