On macOS, you always get your own 'timeline' for the AudioUnit session, so timestamps start from 0.
On iOS however, AudioUnit seems to give you a 'shared' timeline so timestamps start at a later, non-0 point in time.
Simply offsetting seems to do the trick.
This was causing osxaudiosrc to not output any sound on iOS.
Regressed in 2df9283d3f2ea06af5ebd6db03a6d545cac52f19
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/7856>
8f5caeb86d