"SEE-THRU" (eg, partially transparent) APPLICATION WINDOWS on iMac

Monterey 12.7.4, 27" retinadisplay, late 2015 vintage.

WTF is going on with the application windows on my iMac?

I'm in a normal mode (eg, not using dark mode or that stuff). I'm working in Premiere, which has a darker grey interface design, and occupies the entire screen real estate whether in full screen mode or otherwise.

I have "ghosting" images of other, lighter-themed apps (for instance, this Safari screen that i'm typing my query into) when I switch back to Premiere.

I also just noticed that, using a screen capture I just took, when I open that screen capture png, it also is translucent; I can drag it around my desktop and see the entire desktop thru the image.

Because it happens with multiple apps, I attribute this to some setting or bug in the OS. Can anyone enlighten me so I can ask better questions and resolve this? This is not how I want my display to work.

1) Safari in front, Premiere behind:

2: Premiere in front. You'll see the Safari window thru the Premiere screen (note the "Ask a question) visible in center top):