New terrain generation in previously loaded chunk.

I was AFK in my world for 2 days (from October 4th to October 6th), and when I came back to my switch, I needed to reconnect my controller. After I did so, I found myself dead, and in an under water cave. I had been in a safe area designed specifically to AFK in. I then spawned at world spawn instead of my bed, and when running back to where my house had been, I found that the terrain was completely new generation, despite having built there prior. I was able to restore the world with a cloud save. 

The images attached are screenshots of my post to twitter which has a video: https://twitter.com/Periodic118_294/status/1445977305793265669?s=20