the subchunk of y=-64 to y=-49 cant save correctly

1. Clear a chunk and leave three blocks;
2. Saved the level, rejoin the world and destroy the three blocks;
3. Saved and Rejoin again, the three blocks is still exist;

This bug can be used to farm items in Skyblock, or throw a game that relies on a void world such as Bedwars, Skywars into chaos.

*This bug is available in 1.19.0~1.20.70