Funny enough, one of the top Google results for "white veganism" is this University of Michigan article. Let's see what they describe as white veganism:

Further, vegans who enable white veganism may have a strict outlook on animal consumption that does not extend leniency to the cultural practices of hunting by Indigenous and traditional peoples, nor their traditional diets containing animal products. Lastly, it is unfortunately common to see vegan activists juxtaposing animal agriculture to historical injustices posed on marginalized communities. Comparing animal agriculture to others’ trauma and historical systems of oppression that still marginalize people today is not inclusive and, if anything, makes people feel unwelcome in the vegan community.

I could point out that the author of this article is white as driven snow, but I think it's more productive to look at what Michael Parenti had to say on the subject. He addresses this sort of appeal to cultural relativism in his book The Culture Struggle:

The reason for respecting other cultures is to avoid doing harm to the people who live in them. But what if certain practices within the culture itself harm segments of the population? What claim, then, does the culture have to being above judgment? In South Africa, for instance, police are frequently dispatched to investigate muti killings, murders committed in order to present a traditional priest with a severed hand or genitals or heart so he can cure a disease or bring some business gain to a supplicant. 51 South African authorities seem to have zero tolerance for this sacred aspect of indigenous culture. Presumably so would the murder victims had they been given a say in the matter.

It's not hard to see how this applies to carnism if you accept the premise of animal personhood.

Vegans don't go to indigenous communities to attack their traditional lifestyle.

Especially since such critiques can be similarly leveled at many aspects of leftism. Every socialist movement has their reactionaries that twist the purpose into something that suits the needs of reaction. For example: 'White Leftism' cannot truly represent leftism, and representing leftism as 'white leftism' to hate on leftism is just an incorrect way of going about it, and ignores the largest contribution to leftism is the Global South.

They're giving ground to reactionaries due to their own reactionary sentiment, because they'd rather be comfortable than challenge their beliefs.

Thats my personal take at least

When i complain about white vegans im actually just complaining about white people, i dont even care if theyre vegan or not. In fact, my views on veganism change complrtely based on what type of white person im making fun of. I am thr ultimate anti-anglo machine. Buy my nerchanidse. Read my literature