What it means
Apple Photos keeps deleted photos and videos in Recently Deleted for 30 days before permanent removal from the iPhone, iCloud and other devices associated with the Apple Account. It is a recovery window for a recent mistake, not an independent copy.
A real-world example
A video deleted yesterday can often be recovered by opening Recently Deleted and choosing Recover. A video removed long before the retention window, or deliberately deleted from that collection, needs a separate backup if one exists.
What to do
Check the collection promptly, authenticate, restore the correct item and verify it opens. Keep an independent copy of irreplaceable images outside the same synced library.
The distinction that matters
Hidden photos are a separate collection; do not assume every missing thumbnail was deleted. If several devices share iCloud Photos, check the same account on another device, but do not expect a synced device to preserve a deletion indefinitely. Apple's Photos guide specifies the retention and removal behavior.
Apple's Photos guide
