Do this on your iPhone (Safari):
- Tap Pick photos and select ~100 photos from your library.
- Watch the progress card below. Note the time and any errors.
- Tap Pick photos again and select the same 100 photos — all should skip as duplicates.
- Reload this page — your library grid must still be there (OPFS persistence).
Note: if your photos are stored in iCloud, iOS downloads each one as the import reads it. You will see the MB counter move during the download, so a slow photo is your connection, not the page.