Background showing through some apps on iMac display

It's not just Chrome, that was just an example. It was showing whatever I have behind it. However I had a system crash while I was out, and after rebooting the machine, on dialabrain's suugestion I tried the "reduce transparency" in Accessibility options. It seems the problem is gone for now. Not sure if that's what did it, as I had never changed any setting in Accessibility before, and I just tried unchecking it without recreating the problem, but anyway, happy it's fixed for now!

Thanks, but that's not my issue. It's not "image persistance" it happens in real time with what is behind the window. For example if I move the Chrome window in the background, it shows through Premiere in the new position immediately. Screen saver timings etc. are not a solution here unfortunately.

Not sure I understand. That would be a terrible feature for video/photo professionals like myself using software like the Adobe CC suite to do visual work on their Macs. It seems more a glitch than any sort of feature as it's not consistent, and like in this case, it did go away after a system crash. Maybe a memory or graphics memory issue. Odd that I don't see other reports of it online, but I can't be alone here!

Thanks. I don't think that was the fix, but I did do it after a system crash, and the problem is gone for now. Unchecking the box doesn't recreate the problem, so it was likely related to whatever caused the crash, memory leak or something. I will keep that option checked for now anyway, and monitor. Cheers!