Last February, JD Vance had a meeting with the AfD leader in Munich, after delivering a stupefying speech at the Munich Security Conference where he accused European nations of failing to defend free speech, calling out Germany in particular. He complained that the AfD was being ostracized and called for it to end. Marco Rubio followed up by calling the designation of the AfD as a right-wing extremist party as "tyranny in disguise."
Actions like these where US leadership is heavily distorting the facts make it much easier for the AfD to present themselves as a legitimate political movement allegedly being wrongfully suppressed by the “authoritarian” incumbents. The AfD currently scores 25% in representative nationwide polls, higher than any other political party in Germany. In some federate-state elections they scored over 30%, in one of them again higher than any other party. You can’t just ignore them as “crazy“.