Does the term "antifa" to refer to anti-fascists come from within or outside of the anti-fascist movement? When did this term start being used and popularized?

I ask this because I see the term "antifa" used mostly by opponents of the anti-fascist movement, the right-wing, and mainstream media. It seems to me this could be a case of "framing"

https://en.wikipedia.org/wiki/Framing_(social_sciences)

where there is an attempt to insert a "slang" form of referring to the movement instead of its full name in order to dissuade support. In most cases where I see it it seems perjorative, or to have a negative connotation, but that may just be source-dependent bias.

In other words, if someone says "I am anti-fascist," or "I am against fascism," most people would say "Well that seems reasonable, most intelligent people don't support fascism". Whereas if you refer to someone as "antifa", it's a word that doesn't immediately have an association, and thus would be easier to assign negative connotations to it (which seems to be happening in a lot of cases).

When did the term "antifa" start being used, and who created and popularized using it?