"Show Desktop" initiates on its own

You have a lot of third party software! If this were happening to me, I would completely uninstall CleanMyMac, Kaspersky, and Malwarebytes and then test things out. If the problem persists, I would look at the Etrecheck categories "Launch Daemons" "Launch Agents", "User Launch Agents" and start uninstalling that stuff until the problem goes away. For example, you have some Wacom tablet stuff there. Perhaps that is causing the problem. There are lots of other possibilities.

The advice you received concerning testing things out in "Safe Mode" is good because it turns off much of the third party stuff; if the problem goes away you know it was third party software. The downside is that your problem sounds intermittent, and it is tough to get much work/play done if you are in safe mode all the time.

FWIW, I have 7 Macs here running every macOS version from High Sierra to Ventura and that has never happened for me. The only thing I can think of is you have some app causing the problem. You didn't say how often it happens but if it's a regular occurrence, I would test while in Safe Mode.

Start up your Mac in safe mode - Apple Support

As suggested above, if you consider the possibility of a third party software conflict, EtreCheck can be used to investigate what is installed.  Give it Full Disk Access. You can post the report here. Someone might spot something.

Perhaps you have accidentally set up a hot corner in Mission control system, preferences (or maybe it just happened to get set.).

We have five Mac of various vintages and models; the earliest is a 2015 21.5" Retina. A sixth we traded in.

We've never had that problem on any of them.

Since it keeps occurring with you, my feeling is you are somehow invoking show desktop without realizing it.