killswitched

I was reading this article on Safari/iOS 13.4.1 on a late model iPhone: https://www.wired.com/story/inside-the-nsas-secret-tool-for-mapping-your-social-network/

While reading the article, my screen went blank, displayed a spinner, then went to the lock screen. I cannot recall experiencing this behavior anytime recently.

Does anyone know why this might have occurred? Is this just a random fluke, or was something served from the wired website to cause this?