bug: incorrect handling of chain block

For some reason, placing chain block down results in it being rendered as nether sprouts client side: <img width="919" height="801" alt="Image" src="https://github.com/user-attachments/assets/3690e676-5b27-45a2-8aa4-debe068ecdfd" /> Affected versions: 1.21.110, 1.21.114, probably others too. Most likely something wrong with extraction of hashed block-network IDs from BDS.