The majority of Germans do not support a ban. It's the completely brainrotten and extreme left that supports it.
The reality is that something between 20-40% voted for them. While there are problematic elements in the AFD, and they're lying populists, they're ultimately just morally bankrupt profiteers. Basically the same as linke and greens, just targeting different demographics. You're probably just the target demographic of those parties, hence your frankly insane view that banning the most popular single party would be a good idea. It would not. It would massively exaggerate the issue and further alienate even bigger chunks of the population.
The issues the AFD are raising need to be resolved. That's the only way to calm things down, but the established parties seem to inept to deliver on that, hence the increasingly problematic situation.