Prevent zoom window from popping up on the screen

So I am on a zoom meeting now, and I am not looking at the screen that they share, instead I do something in the browser. Why does the zoom window every now and then pops up on my screen and is the only window seen? This didn't happen in the past and now out of a sudden it shows on my screen when not asked to. Is this a bug? If not, how to turn this off?