systemd/camera-streamer-libcamera.service line 15 should be
--camera-format=${FORMAT} \
instead of
--camera-format=YUYV \
as whatever the settings in the libcamera.conf, the video format is alway set to YUYV when used with a pi cam V1
pi@raspoctotprint:/etc/systemd $ ps -fax | grep camera
2554 pts/0 S+ 0:00 _ grep --color=auto camera
2417 ? SNLsl 0:01 /usr/bin/camera-streamer --http-port=8080 --camera-type=libcamera --camera-path=/base/soc/i2c0mux/i2c@1/ov5647@36 --camera-format=YUYV --camera-width=1920 --camera-height=1080 --camera-video.height=720 --camera-snapshot.height=1080 --camera-fps=24 --camera-nbufs=2