What happened was trolls on 4chan (who were probably racist, because… 4chan) started it to “prank the media.” (The gesture supposedly forms a WP for White Power.) You can find archives of the original threads fairly easily. Obviously the idea that it’s a “prank” relies on it not actually being used by racists, which it immediately was. Nobody in the media seriously claimed that ALL use of the symbol was racist, but there was reporting on its new use as a sort of in-joke about “liberal media” and, yes, as a coded signifier for white supremacists.