Summary:
Incomplete blocks underwater have a small problem. If a player underwater aims at waterlogged blocks (only in a straight line, not diagonally) through incomplete block, his aim will pass through the adjacent waterlogged block.
However, when the player's aiming goes beyond the boundaries of a full block (as if the block the player is aiming through was full), the aiming to the adjacent block becomes correct.
If there are no blocks nearby (except for the neighboring tested one), and the player's aiming got into the "blind zone" when trying to break the block, the block will be broken even without aiming.

Steps to reproduce:

1. Place an incomplete block (preferably with a small hitbox).
2. Place a waterlogged block next to (not diagonally).
3. Aim at the waterlogged block through the incomplete block.
4. Try to break the waterlogged block.

Observed results:
Under water aiming does not work correctly with waterlogged blocks through incomplete blocks.

Expected results:
Aiming should work correctly under all circumstances and with any blocks.

Video:
Minecraft Preview 2022-02-15 00-14-24.mp4
Minecraft Preview 2022-02-15 00-09-35.mp4
Minecraft Preview 2022-02-15 00-17-44.mp4