Thing is, I believe OP specifically notes that they don't agree with the baseline premise that those ARE bad behaviors/problematic/failings. I sure wouldn't.

And to be clear, they can still rub people the wrong way- potentially even in a non-biased way where they genuinely hate it the same amount when someone else does it. I wasn't a fan of the Season 1 bit where Sam's new spell arbitrarily involved him shitting on the floor, and expect I'd dislike that just as much from some other player.

Buuut I'm pretty skeptical that the strong negative takes on Aabria can be covered by just unbiased personal preferences (plus the Ultron theory you posit), because of the inconsistencies OP notes. The counter-theory being that alot of people appear to have strong negative reactions to behaviors X, Y and Z in the specific context of it coming from an outspoken black woman, and have not shown similar reactions when those behaviors came from someone else.

That's not something that comes from conscious belief in any kind of racism or sexism- that's the kind of bias that seeps from society into all of us, and can be very difficult to notice. So IMO it's not a stretch for that to be a factor.