For one of my online CS classes, I was accused of plagiarism on a homework assignment.

The course policy is that we can use information from any internet article on the homework as long as we cite the source.

I got a 0 on the homework because the TA claimed my solution "wasn't cited or was too similar to the cited source" (pre-automated response they selected on Gradescope)

I then pointed out that I cited the source. The TA said that they didn't see I had cited it before but would still need to "check with the professor". They then gave the assignment to the professor to look at, and he determined that there was 1 sentence that was "too similar" in wording to the source and maintained I had plagiarized.

I ran my response and the article through a plagiarism checker/text comparison tool which found 0 instances of similar wording. In other words, I paraphrased everything and added my own information.

Is this worth fighting or will they try to take it up to the Academic review board, fuck me out of due process, and hit me with something that will actually be on my record?

No, I don't go to a third world university.