I used to capitalize it, because, as a writer, my brain says capitalize it as it is a proper noun and/or acronym depending on which group we are writing and if we're spelling it all out of not. Now, I've gone sub-script, because they are a sub-species of sub-human trash.
antifa
Its so easy any of you can do it, type the word, highlight it, go to your text edit bar, click the BIG X with the little number 2 hanging off the end. BAM. Subscripted.