I think you got downvoted because the term/group Antifa has existed in several forms since the 30s, it was a movement started in Germany in response to the rise of the SPD between WWI and WWII.
That I did not know. I just know no one was using the term online before trump started calling the BLM protestors antifa. (However, there was a single tweet with an #antifa hashtag 2 days before trump used the terminology. I figured he saw the tweet and it inspired Trump to pick up the term, but now I do not know given the historical back stop.)