I believe that a lot of it has to do with her being a non-white woman.

Obviously, something like 30-40% of people had already picked a side and were going to vote either Trump or whoever was not Trump on the other ticket. But, there are still plenty of people in the middle. Given how extreme the US is, the "middle" isn't reasonable, thoughtful people. They're all voting for the democrats. It's racists who don't think abortion should be banned. It's sexists who are concerned with corruption. It's people who are in the alt-right bubble and think that George Soros and Bill Gates are using mosquitoes to infect people with 5G... but who think Trump is a Freemason, so you can't vote for him.