Apparently the iOS client doesn’t keep track of which files it’s already uploaded; instead, it uploads anything it doesn’t see in the sync folder on the server.
A little more context: I’m using Nextcloud mainly for photos. I have an Android and my wife has iPhone. I have a cron job running on the server that uses exiftool to standardize filenames and metadata, converts .mov files to .mp4, and moves all the finished products to a subfolder so everything is organized by date.
When the iPhone sees that the file is no longer in the upload directory, it sends it again. I don’t have “upload whole camera roll” selected. The Android client doesn’t do this.
Thanks in advance for the help.