I think it more has to do with non-POC needing to be aware of how their words come off to POC. I don't think it's white shaming, imho.
It has to do with the fact that (especially in the English-speaking world) white people are typically the majority, so if they thoughtlessly write about a POC without considering how said group wants to be depicted, they may be overwriting the POC's voice, which has been marginalized for so long. (This goes into the cultural appropriation topic, which I don't want to get into.)
But basically, as an example, if a white person writes about a Native American person and includes strange language (perhaps with food as a descriptor), it might be a bit insensitive to the identity of that particular cultural group. This might not even be the author's intent, but it can be unintentionally harmful. Especially, if this work of fiction gets famous, when not many works by Native Americans do.
It isn't about white-shaming, it's just a sensitivity thing, and understanding that if you are not a part of an ethnic group, you don't know how your words about that group will be perceived. So do your research, and maybe find some sensitivity readers.