I have created a completely artificial area in The End in the XBox One edition which migrating it totally mungling around the edges.   I have basically demolished the original end completely and in my new creation I started with level markers around the edges of theEnd as shown in the attached screenshot.  When I migrate to Bedrock edition, the first 2-4 blocks around the edges are destroyed or changed into something else, and end stone is added randomly near the edges mostly outside the original boundaries.  As a result, the entire scaffolding shown in the screenshot is missing, and areas I have already completed are messed up around where the old edge of the world was.

Update: The issue also exists for the Nether.  I don't know if it exists on the Overworld because I haven't done any grand scale engineering projects near the world's edge there.

 I added two new pictures to demonstrate the extent of the damage.  "top_view_before.png" shows the scaffolding on the sides of the end, as well as the full layout of the first level.  "top_view_after.png" shows the map after a partial second level was added and then the map migrated to bedrock.  Up to TEN ( ! ) blocks were destroyed all around the edges.  This is most clearly seen in the left and ride sides in the middle of the image where no second level construction is obscuring anything.  The top view after image was taken after an hour or so was spent just getting rid of end_stone which had encroached on the boundaries (replacing it with air).