Dismissing an argument on the sole basis of some superficial analogies and/or alleged connections with the Nazi party or the nazist ideology.
General form:
"A sounds nazist, therefore A is wrong."
Typical example:
"I don't think people who carry severe inheritable genetic disorders should be allowed to reproduce."
"Do you realize you're literally promoting eugenics? That's exactly what the Nazis did! You should be ashamed of yourself!"
Just because something was done/said/thought by the Nazis, that doesn't automatically make that thing inherently "nazist", and even if it did, that alone doesn't automatically prove it false or bad.