I didn't want to complicate my original post, but I'm seeing the car occasionally "freak out", disable traction control, ABS, regen, and power brake and steering assist, only to return a few minutes later. I thought I might be chasing a bad ground, ABS wheel speed sensor, etc. At first, my next step was to pull the frunk liner and check/clean the ground studs, but replacing the battery is now an obvious first step.