Platner was subject to one of the most intense smear campaigns in the history of modern electoral politics. Despite a platform that would make him one of the Senate’s most left-wing members (along with Bernie Sanders and, if he wins his own race, Abdul El-Sayed), he was widely accused of being a secret Nazi
It's not really a "smear" when dude is a former state thug with a nazi tattoo, but I guess he removed/covered it up? Ok, but can't blame people for being upset.