Hey so, they officially did away with the whole "being black means you were less faithful to Jesus in the pre-earth life" thing, which hey, great, but it's still in their chief holy book that dark skin was a curse God placed on native americans so that "good people" would know not to associate with them except to try and convert them (and certainly not to have kids with them, because that meant literally passing a curse on to your children.) Also, a central tenant of their belief system is that they (the mormons) understand the culture and religion of both native americans and jews better than they (the aforementioned ethnic groups) do.
So when we say "Mormons are white supremacists," we don't mean that your statistically average Mormon is more likely to ascribe to white supremacy than the average non-Mormon. We mean that white supremacy is baked in to the foundations of the religion. That Mormonism is a white supremacist organization. That those who practice it, at best, are not bothered by that fact enough to leave
Now, I grew up Mormon. Untill I was 25 I was what was called a Peter Priesthood, which is a Mormon who's so Mormon the other Mormons make fun of him for it. So I have a lot of sympathy for individuals manipulated by the Mormon church's cult tactics into sticking to that belief system. I get it, I get how powerful all that stuff is from first hand experience.
But the fact that I sympathize does not change the fact that members are socially and financially supporting an organization that espouses mysoginy, white supremacy, classism, and queerphobia, among other things.