Weird gallery behavior

[mike8668]

Oreo 8.1.0
Galaxy Halo j727

For some reason my gallery app is showing blank grey squares with exclamation point in them.
This happen by itself at random times.
Any idea what's causing this?
Should i be concerned?

(black square=my censorship)

 

[anti-duck]

Oreo 8.1.0
Galaxy Halo j727

For some reason my gallery app is showing blank grey squares with exclamation point in them.
This happen by itself at random times.
Any idea what's causing this?
Should i be concerned?

(black square=my censorship)

My old phone (Swift 2X) used to do that when it couldn't access images stored on the SD card.