h264_v4l2m2m does not produce output #7

ffmpeg version 4.3.5-110222 attempting to read up rtsp (h264 (h264_v4l2m2m) -> rawvideo (native))
displays this
[h264_v4l2m2m @ 0x11336c40] Using device /dev/video10
[h264_v4l2m2m @ 0x11336c40] driver 'bcm2835-codec' on card 'bcm2835-codec-decode' in mplane mode
[h264_v4l2m2m @ 0x11336c40] requesting formats: output=H264 capture=YU12
and then errors with
Finishing stream 0:0 without any data written to it.14:32:22.77 bitrate= -0.0kbits/s speed=N/A
[swscaler @ 0x113195f0] deprecated pixel format used, make sure you did set range correctly
while
ffmpeg version pi/4.3.4/rpi_14-34-gbab9bf4a2e-110122
does work and displays this
[h264_v4l2m2m @ 0xe96dc40] level=30
[h264_v4l2m2m @ 0xe96dc40] Using device /dev/video10
[h264_v4l2m2m @ 0xe96dc40] driver 'bcm2835-codec' on card 'bcm2835-codec-decode' in mplane mode
[h264_v4l2m2m @ 0xe96dc40] requesting formats: output=H264 capture=NV12
Stream mapping:
Stream #0:0 -> #0:0 (h264 (h264_v4l2m2m) -> rawvideo (native))
Press [q] to stop, [?] for help
Output #0, rawvideo, to 'test':
Metadata:
title : Media Server
encoder : Lavf58.45.100
Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 704x480, q=2-31, 20275 kb/s, 5 fps, 5 tbn, 5 tbc
Metadata:
encoder : Lavc58.91.100 rawvideo
frame= 36 fps= 18 q=-0.0 Lsize= 17820kB time=00:00:07.20 bitrate=20275.2kbits/s dup=8 drop=6 speed=3.67x
video:17820kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.000000%