With the new IDs introduced in the flattening snapshot, we got:

• X_bricks for full blocks
• X_brick_slab for slabs
• X_brick_stairs for stairs

However, in the latest snapshot, 3 slabs and 3 stairs were added, and prismarine bricks ones are named prismarine_bricks_slab and prismarine_bricks_stairs
Just an inconsistency.