The piece is called Peanut Butter Platform, and it was ‘created’ in 1962 by Wim T. Schippers. The Museum Boijmans Van Beuningen acquired the piece earlier this year but refused to put up a fence around the piece. This isn’t the first time in Peanut Butter Platform’s life that someone has stepped in it.
Sort of absurdly the museum is seeking damages from the stepper. While researching this piece I saw that the floor was painted with peanut butter when the piece was installed, so it’s not like this is some irreplaceable work of art - they probably regularly re-butter it.