Several students have called me and were accused of cheating on an exam. All from different universities with a similar issue. The students excused themselves to go to the bathroom and took their phone with them. Then while in the bathroom, they access an online portal like canvas or notes on a web-page. All of this is done while on the school Wi-Fi. They then score higher than usual or had similar answers to other sources and are flagged for cheating. The student denies this but then the school offers up evidence that your phone was sending and receiving data during exam time.
The school may not be able to tell what you looked at, but they know you accessed something. If your phone is active while you are taking an exam, it looks bad.
Turn off your phone or at least your Wi-Fi while taking an exam. If you are already accused of cheating, there are defenses but what those defenses are depends on your unique situation.