I am using the default settings. Here is my modlist: https://pastebin.com/rHMhzFfk
I just generate the default world with no settings changed, the world is all desert. The behavior doesn't exist when I remove your mod.
https://imgur.com/ui7bMfh
If you set type of tiles to pave to None it shouldn't do that anymore. If it still does do that can you send me a save with all mods installed where it happens?