Buried Treasure cannot generate if there's no suitable stone below its generate position in 1.18+.

Steps to reproduce:

Seed:892313478237648

/tp 73 -27 -599  (The water is 90 blocks deep here)

Then run the command

/locate structure buried_treasure 

It will say it's 0 blocks away.

Then dig down, you won't find any buried treasure.

Analysis:

Buried Treasure always generates 1 block higher than the highest suitable stone at its X and Z coordinates.

Suitable stone includes:

Stone, Sandstone. Diorite, Granite, Andesite.

But if there's no such stone at it's X and Z coordinates, it won't generate.

There's no these type of stone below Y=0, so it can't generate below Y=0.

(For proof, you can create a default superflat world or a only-deepslate superflat world, then run the command /place structure minecraft:buried_treasure ~ ~ ~ , and you will found it is "placed" but no buried treasure chest generated. Then create a superflat world with only suitable types of stone, run the command /place structure minecraft:buried_treasure ~ ~ ~ , and you will found the buried treasure chest is generated.)