We have ffmpeg-based code that runs on both iOS and Macos. We've noticed, that with the upgrade from iOS 14 -> iOS 15 videotoolbox decoder started failing to process h264 stream.
Today we've finally dug a bit deeper into this, and it seems the failure is similar on iOS 15, and on MacOS 12.3 -- but only on Apply Silicon for the latter. The same software and input work fine on Intel Mac.
The failure is explained in some detail here: https://trac.ffmpeg.org/ticket/9713
and here:
https://trac.ffmpeg.org/ticket/9016
It is quite easily reproduced with ffmpeg