When a person of color, especially if they're black like me, affirms their support for causes such as queer liberation, feminism, animal rights, or socialism, I immediately feel that I can believe, with minimal doubt, that they're truly convicted and principled in what they're advocating for.
However, when a white person claims to support leftism, until my skepticism is proven wrong, I immediately assume they're a dishonest and performative libshit. I then proceed to interact with them with hefty amounts of caution. If my assumptions are proven true, I'm never shocked.
It is reasonable to have these suspicions. In my everyday life I feel infuriated hearing the racist shit the white people I work with may bring up around me, since they assume that I'll agree with them since I'm white too. Most of the shit they talk about is their callous obsession with the oppressed migrants at the southern border. If that's what those people do openly and outwardly express, I can imagine just as well that there are white leftists who have not examined and gotten rid of all their prejudices. It's reasonable to think they have just used their knowledge of left norms and attitudes to hide it way better than the chuds I see irl. I'd say your vigilance is warranted.
I hate how the continued existence of these racial hierarchies poison the minds of so many white people, teaching them a multitude of ways to be alienated from their fellow human beings. The task of the left in dismantling these oppressive hierarchies is a Herculean one, requiring massive socioeconomic changes and I at times despair when thinking of its chances of success in the heart of empire during such a turbulent time in human history.