On the late November 2021, I created a new, fresh hardcore as I took a break from Minecraft because on the late April 2021, I died on my 600 day Hardcore. One day on early January 2022, I played my hardcore which was at around 150 days at that time, and I chose to explore out of my base with an elytra. As I flew back home, I spotted something extremely strange, I saw a dug up pit of sand I never touched on that world. Then it hit me, somehow this dug up pit of sand in the desert biome is the same pit that I dup up in my old, 8 months ago, 600 day hardcore. I never touched that hardcore in those 8 months nor I altered my current hardcore to cheat. I created the new hardcore world fresh. I cannot explain how this has happened. Then all of a sudden, I also spot the same sand hill which was near the dup up sand from my old hardcore world in my new one. I do not know how this happened. I do not know if this was Minecraft's chunk loading for new world messed up, I do not know!
What is even stranger that when I did /seed in my current hardcore world and used it to create a creative world to see if this happens to it as well, when I wrote the coordinates from the sand pit and teleported, there was not even a desert biome. It was just an ocean biome.
I do not know and need answers.
There are also these walls in the nether that are completely flat and on the other side there is some part of the nether from my old world