Minecraft: SuperFlat Problem?

I have just creating a TNT Canon. Then after that, I changed my render distance to FAR so I can see the explosion. I go to the explosion then suddenly, I saw a "Normal World" chunk. I don't know what is this but I think its a glitch. I also restart the game but it didn't work. Can someone help?

Thanks!

Added (1). Also, it makes a long long long Normal World chunks which it will surrounds all of the world.

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