@edent What I'm saying is that in normal usage, hitting the Upload button on MacOS or iOS should never result in a HEIC file being uploaded - Apple has built in lots of protections to prevent that from happening - JPG conversion is automatic. I did some research this morning and found one article speculating on why this happens sometimes - some users back up their library with tools like Dropbox to another location. If they were to upload from Dropbox rather than normally from their Photos library, the auto-conversion would not happen. That's the closest I found to an explanation anyway. Apple has carefully designed things so that this should never happen, but if files "leak" out of their container, it does. And apparently it happens more often than I thought!