There is distinctly racist imagery connecting Black people with apes of all sorts. As such, whenever that sort of imagery is invoked, even unintentionally, I'm prone to call foul. There is no such association with bug monsters or whatever. Like Tousen was a poorly written character whose end was unsatisfactory but I thought his normal form was a great design and I see nothing offensive, even accidentally, about his hollow form (it was stupid and ugly though). Like human villains turning into monsters is such a normal thing (and happened to tons of the villains in Bleach) in fiction in general that I'm not going to call foul unless it crosses with real world racist stereotypes.
With regard to Yourichi, I do think it sucks she couldn't finish the job and wasn't give the win - that she needed someone to swoop in to finish the fight. However, berserker/feral forms are a dime a dozen for protagonists in fiction and there is no long standing, to my knowledge, inherently racist association with people of color and cats (unlike for apes). Like why should I find that offensive from a racism standpoint?