he BSW does that currently and has gone into a long conflict with justice, it won't..
The BSW has (slightly) less than 5% of the votes and was never in government. The amount of damage they can do is limited.
of course the AfD will do the same!
The difference is that those parties (except for the Left party, but they have never been in a federal government and key positions) are pillars of our democracy. There is no doubt that their politicians are commited to our democracy, and their voters are unlikely to symphatize with attempts to destroy our democracy.
The AfD however... Every prominent politicians has made statements that raise serious doubts about their convictions. And less-prominent politicians are often even worse.
but for that the AfD needs to be officially "verboten" first!
Not necessarily. You can already be barred from e.g. working in Civil Service if there are reasonable doubts about your loyalty towards the liberal democratic basic order (interesting translation of freiheitlich-demokratische Grundordnung). Without going into too much detail, membership in a party that promotes views that go against the constitution can be used as source for those doubts, even if the party has not been banned yet.
Right now the AfD voter don't act like revoluzzer!
Well, many of those who tried to stop the confirmation of Joe Biden in 2021 had never come into conflict with the law before. The only red flag in hindsight was that they blindly followed a man who made up stories about election fraud and had systematically undermined democratic institutions while in power.
Personally, I'd argue that anyone who looks at Höcke and thinks while knowing what he has said and done "Yep, this guy would make a fine minister resident" should do some soul-searching about our history and democracy.
Final thoughts: The AfD is looking for inspiration in other countries. They have seen that their counterparts in France and Italy have found success by appealing to a broader audience. They however despise what they call "Melonization" after PM Meloni and instead go futher to the right. They have however noticed that perceived historical injustice is a powerful tool for agitation. Not unlike the far left, with whom they have surprisingly much in common (e.g. regarding their views on Putin). Unlike the far left, they don't talk about reparations for former colonies, but like PiS demand reparations for supposedly unsettled wrongs from WWII.
Which is what concerns me. So far, Polish-German ties have suffered quite a bit already due to those unfounded reparation claims from some polish parties. What happens if the AfD adds to the toxicity? That is a recipee for disaster in the long-term.
