The place is called hatWRKS ... and they posted a since-deleted Instagram photo featuring a woman proudly rocking a yellow patch -- made in the same style as what Nazis used to brand Jews with in the midst of the Holocaust -- with lettering reading, "Not Vaccinated."

There's a cold-blooded caption attached too, which says ... "patches are here!!! they turned out great. $5ea. strong adhesive back .... we'll be offering trucker caps soon."

Of course, the post caused an uproar online and elsewhere -- and rightly so. People note that comparing what happened to Jewish people to what anti-vaxxers perceive is happening to them right now is absolutely ludicrous, asinine ... and downright wrong. They're not the same -- not even close, and trivializing that history with a patch like this is beyond offensive.

So, what do the owners of this mom-and-pop shop have to say for themselves??? Apparently nothing so far -- it doesn't seem they've responded to the mounting criticism, other than removing the grotesque photo.