The Bug:

Ruined portals can generate with air pockets when generating in aquifers and rivers.

Here is an example:

Seed: -7904429713016255202
Coordinates: /execute in minecraft:overworld run tp @s 121795.94 56.28 4575.82 -34.40 49.73

Steps to Reproduce:

1. Generate a world with the seed provided above and teleport to the given coordinates.
2. Look closely at the ruined portal.
3. Take note as to whether or not ruined portals can generate with air pockets when generating in aquifers and rivers.

Observed Behavior:

Ruined portals can generate with air pockets.

Expected Behavior:

Ruined portals would not be able to generate with air pockets.