If the US government deems "Antifa" to be a terrorist organization, this is likely to have widespread consequences because (post PATRIOT ACT) banks are held *liable* if they transfer money that is related to money laundering or terrorism.
So, they're terrified because the possibility for fines is "infinite".
Traditionally, "terrorism" was really just something that existed in the middle east and for the most part, banks just didn't worry about it.
But if you have a domestic terrorism designation, then things like GoFundMe could become too risky for a payment processor to touch. You could even imagine mass-unbanking of leftists. I don't think that will happen, but only because it's bad for business, the law is pretty clear - if money goes to a terrorist organization, the financial institution that wired it is held liable.