I was just loading up my first 1.18 world and I noticed that at the border between a snowy slopes biome and a plains biome, as you moved into the plains biome, there were several patches of snowy slopes biome that do not look like they should be there.

Here is my world download on Google Drive, if you need it. I am putting it here because it is too large to attach.

https://drive.google.com/file/d/1hydybvkK45zSXSgaVjk4EfZs5KKj4_NV/view?usp=sharing