To be clear I think this bill is horrendous, but...
The non-profit will have 90 days to “appeal.” Without having any idea what they’re being accused of.
This is not quite true. In Section 4 C (ii) it states that the secretary must provide "the name of the organization or organizations with respect to which the Secretary has determined such organization provided material support" and in Section 4 C (iii) it states that the secretary must provide "a description of such material support or resources to the extent consistent with national security and law enforcement interests."
That doesn't lessen the chilling effect this bill will have nor will it lessen the damage caused. But I feel accuracy in discussing this is important.
After this bill, Trump will declare antifa, BLM, and pro-palestine movements as terrorist organizations
Possibly. But per the bill they have to at least make a show of "proving" that the organizations aided designated foreign or domestic terrorist organizations, which is defined by the Secretary of State. Yes, of course they can just define an organization as such but it's not completely evidence-free. I'm a little unclear on the process of domestic vs foreign designations - Executive Order 13224 signed by bush gives both to the Secretary of State. Still that way?
"Then all leftist legal support is dead"
Because people can't get a tax deduction? I'd hope we're slightly better than that.