It hadn't been driven in a couple days, and it was slightly below 0 C. So I guess it's possible something froze, but it wasn't excessively cold out.

I am mostly a one-pedal/regen driver, but the brakes had to have been working a few days prior because the car doesn't fully stop without using the hydraulic brakes to go from low speed -> stopped.

But after low speed testing in the parking lot I turned into I couldn't reproduce any failure so I barely had anything to report that would have been credible.

I also learned that you can't slam on the parking break (what I would have called an emergency brake in other cars!) because it's software-disabled above very low speeds.