This can happen, on an iPhone, if you deleted photos using the Web version of Google Photos (deleting the cloud copy) and you didn’t open “Out-of-Sync changes” on the phone and also delete from there. That means the Google Photos (cloud) copy is gone – it’s in the trash, but the photo is still stored on your device. You can see it if you open the Apple Photos app.

Since the deleted photos are in the trash – the Google Photos app knows not to display them. When you manually remove them from your trash, or 60 days go by and the photos are automatically removed, the Google Photos app is now free to display the photos that are stored on your iPhone – the ones that you previously deleted.

They’re BaAAck

As long as they’re in the trash, Google Photos knows not to display them. Once they’re gone from the trash, but still on the iPhone, Google Photos will re-display the device copy.

Note: this does not happen on the Android version because, when you delete photos from the trash you also give permission to delete the device copy.

Learn more …

• Article: How to delete photos from Google Photos: delete from cloud, phone, or both?
• Google Photos Experts page: Deleted photos and videos