Guilt by association
Guilt by association is a form of ad hominem in which the reputation of an individual/organization/movement is attacked by associating it with another individual/organization/movement with a bad reputation.
To associate critics of some form of political correctness, regardless of ideology, with National Socialism, is a common example. Such an association can be created emotionally despite there being no logical cause for this and despite no open argumentation being stated. One example is by illustrating articles criticizing ideological opponents with images with National Socialist imagery despite there being no logical cause for this.