The bug

Sculk shrieker blocks have four faces on the inside. These faces can only be seen by clipping inside of the block, and are otherwise never visible, making them completely redundant. Said faces do not exist at all in Java Edition, so this counts as a parity issue.

Note that these faces are different from the faces used for rendering the four protrusions at the top of the block - this is evident as said faces are not coplanar.

How to reproduce

1. Place a sculk shrieker in midair
2. Enter Spectator mode
3. Fly inside

Expected results

When inside of the sculk shrieker, you shouldn't be able to see four horizontal faces.

Actual results

You can.