Comment by forgotthetimer

(OP, temp user, forgot to disable the HN procrastination timer)

For anyone trying to do this in the future, here's the command to stream from a modern Pi camera module / driver to twitch. IIRC I also had to install the full version of the libcamera tools to use the libav switches.

    libcamera-vid -v 0 -t 0 --codec libav --libav-format flv -o "rtmp://<twitch stream url>/<twitch stream key>" --rotation 180 --width 1920 --height 1080 --framerate 30 --bitrate 4000000 --autofocus-mode auto --autofocus-window 0.25,0.15,0.5,0.5