Broken as in there was no official working binary last time I checked. Maybe the binary does build but I quite liked the auto preview and other GUI features.

> Graphviz.app currently doesn’t build on OSX Mojave because of Apple API changes. It would be wonderful if someone can fix this.

https://graphviz.gitlab.io/download/

It's a general theme that Apple doesn't take compatibility very seriously but each case is annoying.