There’s a movement within black metal that calls itself “National Socialist Black Metal” (NSBM). It’s what happens when any group of dickheads insert themselves into an existing scene or genre. Similar thing happened to skinhead punks in England in the 80s.

Some times it boils down to here’s a black metal band comprised solely of neo-Nazis and while they sing songs about trolls and despair they also do Nazi shit in their spare time. This only fuels the assertion you made earlier because a lot of times you can’t even tell they are NSBM from the music, you have to have read an interview, listened to their stage banter, or looked up a list of known NSBM-adjacent bands.