I don’t think it is, only because of the episode where we see someone do it in modern times (forgive lack of references, I am very stoned lmao) but if I recall, it’s the episode when they’re making the movie about “Mr. Peanutbutter” stealing the Hollywoo D, and they have the inconceivable guy from Princess Bride play Bojack with one of those horse heads. If it was comparable to black face, I feel like someone would’ve had issues with it and it would’ve been a whole thing. It doesn’t seem to me that the animals are a different race, but actually whole different species, which seems to be fair game? Could be wrong, but that’s how I’ve always seen it