samsung – Unknown “keyhole gallery icon” sometimes appears on lock screen?

Sometimes on my lock screen, an icon with what looks like a keyhole and some sort of gallery-related image appears for a few seconds and then disappears. It happens randomly when I turn on the screen on my phone. It shows among the other notification icons in the middle of the lock screen, and it always disappears by itself after a few seconds even if I don’t unlock the phone.

Samsung keyhole gallery icon

The phone is a Samsung Galaxy S10.

I can’t find any settings or apps that seem related or that have this icon, and I can’t find the icon when Googling either.