So I fixed it, FWIW. The issue was the face was just massively open, which you could see was the main difference between the two swings. I was doing a few things differently that caused this:
At setup, I would open my shoulders more to try and promote an I-O path, which only caused the face to open more. To fix this, I now setup with my trail arm slightly "higher" or closer to the ball at setup. Not a lot, but a bit
On the downswing, I now try to consciously swing in to out, but also try to get my trail arm back to that position, so feel like it's closer to the ball at impact than my lead arm, which closes the face.
Thanks to all who responded