I was on my CB scrolling in FB feed videos and suddenly A large pop up appeared. It said it was a windows defender security alert. If I took my cursor out of the large square it disappeared. So I could not turn my CB off. I had to turn it off manually. I realize they wanted me to click on things and call a phone number but of course I didn't. Of course I don't have windows defender etc.

Has anyone had this happen to them. Why can this happen on a Chromebook?