Earlier quoted context omitted.
Some of their ex-members have been literal Nazis. Something that doesn't go over very well in Germany. The party banned these people but their standpoints are still very controversial, the main issue is that in some aspects they do no support the juridical system. So yeah, regular right wing compared to American standards but I think we can all agree that respecting the trias politica is a good thing in any country.
I’ll be honest, as an American looking in from the outside, this looks like the leftist parties in Germany trying to silence the opposition. If the party is expelling the true extremists like the Neo-Nazi former party members that you mentioned, I don’t see why they should be held responsible for them. This would be like declaring the entire American Republican Party extreme-far right because of a few whack jobs like…
I'll abstain from making any moral judgements about this, I don't feel qualified to do so but I understand that the historical context places a very large role in Germany.
Any association with Nazi's is condemned in the harshest way. The AfD has crossed that line several times in the past.