NOTE: This happened on the BETA and my issue ticket was deleted as a duplicate. So you should have been aware of this major bug before the release.

Here's a video I made on the issue: https://www.youtube.com/watch?v=S1weRMd95cY

Basically, multiple chunks of my world got regenerated when I synced them from the Xbox One version to the Bedrock, or whatever, version. Like I said, this bug was on the BETA version of the game and the same exact chunks are getting regenerated multiple times, over and over again.