I am using the latest IOS with the latest Nextcloud app and got the photo sync activated.
After I was viewing some photos using the default photos app on my iPhone the Nextcloud app is uploading those “viewed” photos again. I didn’t make any changes to the photo but nevertheless nextcloud app is re-uploading the photos. This leads to duplicates and is disturbing if you have large collections of photos. As you always have to remove the duplicates. Somehow the app thinks the photos got modified, which isn’t the case.