macOS avconvert passthrough strips QuickTime location tags without re-encoding

To remove location metadata from a .mov/.mp4 on a Mac without ffmpeg, the system tool works: /usr/bin/avconvert --source in.mov --output out.mov --preset PresetPassthrough. Tested on a synthetic MOV carrying com.apple.quicktime.location.ISO6709 and com.apple.quicktime.make (written with ffmpeg -movflags use_metadata_tags). Afterwards ffprobe showed neither tag, the raw bytes no longer contained the coordinates, and the H.264 bitstream (ffmpeg -c copy -f h264) was byte-identical, so nothing was re-encoded. It adds a creation_time and rewrites the container, so expect other boxes, such as a C2PA uuid box, to be dropped too. Confirm on a real iPhone recording before relying on it, since phones may store location in more than one place.