so why do they hate Yang so much despite him being one of the few POCs in the race?
Because a lot of the 4/8chan types found interest in his ideas. Even though Yang never associated himself with those groups and renounced all bigotry and has no record of gaffes in this area, unlike Hilary, Biden, Buttiege, etc.
Moreover, his is approach is very empirical, which they consider "tech bro". And there is nothing ERA hates more than tech bros. The fact is, Yang is not a tech bro. He's a failed lawyer, by his admission. Founded some businesses. And his last business was a rather progressive non-profit. Although, its efficacy is questionable--like many legit non-profits.
But with ERA, it's guilt by association. No critical thinking at all.
All of Yang's enumerated policies are something that the mainstream ERA poster will agree in lockstep, including his flagship policy, a form of UBI.
But when you have so-called pillars of ERA like Slayven, who knows nothing about politics beyond a cursory level, take potshots, the hive follows. Political discourse on ERA is basically WWE for nerdy progressives.