Dim images on Desktop

[BGPL]

I started noticing this in Ventura and it continues in Sonoma, and now I'm seeing if anyone can provide an explanation for some odd behavior. I can't find anything on this elsewhere and I've searched several times.

Scenario:
Some image thumbnails on my Desktop are dim and others are not. I checked attributes and there are no hidden attributes as far as I can tell. As a test I screen captured a portion of a webpage twice in the same area within seconds (Images A-1 and B-1). I did another test of a smaller area of the page (Images A-2 and B-2). One is dim and the other is not. If I keep taking screen captures, it will be random dim vs normal (it is not every other image for organization or easy viewing). My Desktop is not iCloud synced. When I view the files in a finder window, they are uniform and not dimmed. If I move the thumbnails around on the desktop, they do not change. When I move the file to another location and then move it back, it is no longer dim.

I'd be interested if anyone else observed this behavior.

 

[BGPL]

Well, I figured out why some are dimmed and some are not about 2 minutes after I posted this - still don't know what is causing the erratic behavior. Turns out, macOS dims the thumbnails of screen captures, which is something I had assumed in Ventura until I started noticing some weren't dimmed. I ran "mdls" in Terminal to capture the metadata attributes of two files, one dim and one normal. The dimmed file has a number of attributes that are not present in the other, including:

"kMDItemIsScreenCapture = 1"
and
"kMDItemScreenCaptureGlobalRect = (
754,
391,
559,
838"

Along with several more. The latter I would assume are the four coordinates of the cursor when the capture was taken, as I did not capture the entire desktop.

It still remains unclear why some files are being written with the attribute kMDItemIsScreenCapture=1, et al, and some are not. It's also interesting that this bug survived two major releases.

I tested on earlier macOS releases and it doesn't occur there. I can't test other machines running Sonoma until tomorrow.