Is Zwarte Piet racist?

In light of the Dutch election, I was reading up on some of the issues and they parallel many of the ones we saw in our last election. One issue relates to a perceived attack by multiculturalists against the Netherlands national customs and holidays. One such custom is to dress up like the character Zwarte Piet, a helper of Sinterklaas (Dutch Santa Claus). It's not hard to guess why people think this character is racist, but is it actually? I know the Dutch are typically pretty racist as a whole, and I know there's another tradition around a royal carriage with images of slavery that has also received a bunch of pushback. Do the Netherlands have a bunch of snowflakes, or are these things just actually racist?