Thanks that makes sense, I'll try to make a fresh installation and see what happens. If that behaves differently (and works) then we know there's something amiss with the setup of your other image.

If you have a spare SD card lying around it might be worth installing the new 32-bit Bullseye with Picamera2 pre-installed. I know it's a thing that should work, but we don't particularly recommend it because the different settings that people may have when they upgrade is very hard to guess at, and the testing burden in trying to guarantee that it works correctly in all cases is very high. The other thing I'm nervous about is upgrading a Buster image. INFO RPI raspberrypi.cpp:761 Sensor: - Selected sensor format: 1640x1232-SBGGR10_1X10 - Selected unicam format: 1640x1232-pBAA

INFO Camera camera.cpp:1035 configuring streams: (0) 1640x1232-YUV420 INFO RPI raspberrypi.cpp:1374 Registered camera to Unicam device /dev/media3 and ISP device /dev/media0 WARN RPI raspberrypi.cpp:1258 Mismatch between Unicam and CamHelper for embedded data usage!

Raspberry pi zero install camera