Is "nazi(s)" always a proper noun?

I got a Scrabble game for my computer and it works well but one of the words my computer opponent used was

NAZI and the it used NAZIS

The game will not let you use proper nouns, so I take it the term nazi isn’t always a proper noun. Or is it?

Is my Scrabble game wrong?

I think it has become that way. Soup nazi, grammar nazis, etc. Used to be a proper name, now has alternate usages.

Webster notes that as both adjective and noun it is “often not capitalized,” which is probably good enough to make it acceptable for Scrabble use.

Interestingly, the term “Nazi” was apparently originally derived from the diminuative for the name “Ignatz”, which had something of the “yokel” connotation that “Bubba” has for Americans.

That’s not what the entry is saying, just that opponents favored the Nazi abbreviation because it also meant a foolish person. The latter sense was derived from Ignatz, not the former.

Here’s the relevant part:

I concur. Big difference between “He’s a nazi” and “He’s a Nazi.” Lowercase nazi could mean anything from somebody who holds views similar to those held by the Nazi party or merely somebody who is controlling and fanatical either generally or in a specific area/activity (e.g. “Don’t be such a radio nazi! I want to listen to some of my music, too, ya know!”) Capital-N Nazi means somebody who is (well, I suppose “was” is more accurate) a member of the Nationalist Socialist Worker’s party.