I'm primarily speaking from personal experience, so please heed my caution, but the irony of the "You can't compare human oppression to animal oppression!" argument lies in the fact that many anti-vegan leftists discriminate against both humans and animals. It seems that the notion that they oppose human oppression is highly performative and disingenuous.

I've experienced too much flat-out bigotry from these kinds of people for it to be transparently obvious that I should even trust the most principled but non-vegan Marxist.

Human oppression and animal oppression clearly go hand in hand, and one way I've noticed this is that, not so uncommonly, people who fail to oppose one will, in some capacity, fail to oppose the other.