Incorrect loading of Pre-set seed "Mushroom Island"

Playing on xbox_one_s

-Create new world

-Survival mode

-Named beta

-Difficulty = hard

-Bonus chest

-Show coordinates

-Seed = Pre-set world "Mushroom Island"

-start game

-go to coordinates 28,65,52

 

The issue is that the island created a broken nether portal, with other foreign blocks to this biome that do not belong.

 

Note, I did not place any of these blocks