Flying in survival mode

Hello.

A few months ago, me and a friend were messing around in a test world. As a joke, I switched him to survival mode, and shortly after to creative again, then back to survival. Just messing around. The weirdness started when he began to fly like he was in creative mode, and to test that he was in survival, I threw a trident at him. Sure enough, he flashed red on screen and shouted at me from the voice chat. I thought this was a bit strange, but didn't pay much attention to it until it happened again a week or two ago in a 173 megabyte survival world. I switched him to creative and to visitor mode so he could spectate what I was doing. When I switched him back to a member and to survival mode, he once again began flying like he was in creative mode.

I'm not sure how to recreate it, but he was also on an Xbox with the same OS version, same Minecraft version, and we were in vanilla both times. The only other thing that could be helpful is the fact that we were on my world both times.