Here’s a link to my commit where I fix the issue you’re describing. I probably should update my OP with this as well: https://github.com/JonGilmore/ha-personal/commit/65b99934b10bbd138d98539e62d7785adcf12631
the tl;dr of it is the X-CSRF-Token was breaking stuff, and it seems unifi changed the behavior of this.