So I got messing around in there, and I found that if I set Corner Barrier to False, and Edge Barrier to 0 pixels, it seems to have taken it away, but just doing either of them by themselves did nothing, which is what I had tried. It does make it hard to snap a window to that quadrant or halfscreen, but I do that much less often than run my mouse across the screen hard up to the bottom or top edge, which was what was catching it.

I'm not even quite sure what either of those are, or if they're supposed to be independent, but they don't act that way. Hot corners in the far left and right of the monitor group still works, which is fine, even though I personally turn them off.