User Billy Kerr suggested modifying the brightness with a dense regular dot pattern. That's not bad except it doesn't explain the variety which is in questioner's example.
The variety can be explained with interaction of two different dot patterns. It's the same as Moire patterns when one tries to scan a printed image. Actually there's also a third pattern, the screen pixels, but it can be eliminated with high enough zoom.
In the next image there's a quite flat BW photo taken from window's image samples. On top of the image is 4x4 pixel BW checkerboard pattern with low opacity and blending mode Multiply. The result is quite same as in Billy Kerr's answer.
The pattern variations in questioner's image seem to follow coarsely contrast borders in his image. I guess the reqular pattern has got a displacement map, which is some version of the image. Maybe a contrast boosted, a little blurred and desaturated version of the image is saved and used as the map in Filter > Distort > Displace. When layered, tn original dot pattern somewhere neutralizes the displaced pattern and somewhere gains it. Here's an example:
The displaced pattern itself has variations for the same reason, the dots are here and there pleated. Having the original pattern, too makes possible to try different mixes with the opacity sliders.
Here's another result with different settings in displament scaling and the opacities: