The Bug:

The generation of ruined portals can cause stone blocks to be found at low altitudes.

The lowest altitude that stone is able to generate at is y -7, but stone blocks can occasionally be found below this height if they were to generate with a ruined portal.

Here is an example:

Seed: 1359968930092793278
Coordinates: /execute in minecraft:overworld run tp @s 3361.79 -44.35 -1779.30 230.85 45.90

Steps to Reproduce:

1. Generate a world with the seed provided above and teleport to the given coordinates.
2. Look closely at the blocks within the ruined portal structure.
3. Take note as to whether or not the generation of ruined portals can cause stone blocks to be found at low altitudes.

Observed Behavior:

The generation of ruined portals can cause stone blocks to be found at low altitudes.

Expected Behavior:

Stone blocks would not be able to be found at low altitudes when they generate with ruined portals. Instead, the stone blocks should not generate or should possibly be replaced with deepslate variants to avoid this issue from occurring.