All server owners have this problem.
Paper
Spigot
Worldedit, a plugin as you know, works with the seed to rebuild parts of the world
//chunk
//regen
and it regenerates complete different chunk
Try it yourself, make a server out of papermc.io or spigotmc.org use a 1.17.1 version of them and a world ofcourse, put in a pluginfolder the right plugins ofcourse, worldedit, permissions plugin like luckperms, go in the world have the right to use a //wand and then do //chunk and when a chunk is selected do //regen.
See that the world is minimally changed. Now go to those websites and use either of them in the 1.18 version, let the world upgrade either through minecraft client or other means, go in that same world and do again //chunk and then //regen

Our result came out that there was a significant not matching chunk that looked horrible.
Now I have contacted the worldedit owner and he said that there was not a change in the command //regen. So, it must be the version of minecraft that uses the worldseed, other things I can not think of.

Hope you understand that this problem is globally, because at every point somewhere in the world a server owner has to repair for whatever reason a piece of the world, and the only way to do this fast is with WORLDEDIT!

I hope you take this serious and will look into this, try this so that I do not think I'm going mad over this

Sincerely,