I too keep porn on the desktop.
I’m more curious why you have your desktop icons edited out of the photo 😅
Have headphones connected? Mine had a volume knob that would randomly do this.
My Cloud Flights used to do this when I was wearing a hoodie at the same time. The volume knob touched the hood and it made the volume change.
That looks like the audio volume notification. I’d check things that could be changing that level.
When pressing the volume buttons on the media keyboard. I get this all the frigging time.
Seems like a malfunctioning volume button on your keyboard/headphones.
You’re probably hitting a volume key on the keyboard by accident
I had a customer with the similar problem. In the end, after trying everything else we realized that the volume button was crooked and jammed on one side in the case. It was an aluminium laptop and the button also so the tilt was small but just enough to hold it stuck.