The black face thing
They are poking fun at every section of society in this show. The black character was the friend of a white character portrayed in the same way (old rich fat women at a beauty spa). Also had ; men dressed as women, characters in wheel chairs, fat shaming, a very perverse mother's boy (bitty!), poor white teenagers. The list goes on and on.
They either, shouldn't have apologised for the black character, or, apologised for all the characters. They were all as insensitive as each other. That's what was so funny about it.
They meant no harm to anyone.