While this has only happened once so far in the middle of gameplay (Diablo 4) the desktop app (PC) popped up over the game with a “What’s New?” ad for a summer sale in a modal window.
I was playing the game for hours and in the middle of a battle when it happened, where I lost all control of the game since focus went to the desktop app ad. This should never happen during gameplay.
Since I was using a controller at the time and not the keyboard, it wasn’t an accidental key combo to change window focus. I had to jump up and run to the keyboard before I died in the game.