Irregularities in chunk generations

Since the 1.19 update, I've noticed erratic chunk generation in my world. There are straight snow walls on mountains, hollow spaces in the oceans, "squares" of forests on rivers, and lighting errors. These issues seem to appear out of nowhere, since these places were already generated normally before. What's happening in my world?
Seed: 42130000

https://1drv.ms/v/s!AhxgGI5XNxXfphC73KDeboESVtUd

https://1drv.ms/v/s!AhxgGI5XNxXfphH-9N4sBoTnSObs