Floating islands are repeatedly generated around the end realm every time I log in to the game

I emptied all the end stones and obsidian pillars around the end realm because I wanted to build a house. But there is a circle of floating islands around the end realm and some fragmentary end stones, no matter how many times I clear (use/fill) or destroy them, they will regenerate the next time I log in to the game.

I want to know if this is a bug, and I hope there is a way to remove them permanently.