Structures and natural decorations get smeared all over mountains in converted 1.17 worlds

so I wanted to test world generation across the 1.18 beta in Minecraft. I didn't have any good words to make backups of so I used an old map I downloaded a year ago and loaded it with caves and cliffs. the map was using the mushroom island seed from the seed picker and I loaded it up and I saw mushrooms shipwrecks and trees smeared and squashed on the newly generated cliffs. I also did that in an old world preset that I made for a video of me fighting the ender dragon in the overworld. (in an infinite one he would just fly till the world border) and I converted that world to infinite and toggled caves and cliffs on. and the fake end pillars I build for the ender dragon to fly around were also messed up. it doesn't matter the seed it's like that in all converted worlds.