Magma Cubes shouldn't spawn when there's only 2 blocks in height. This gets ignored and slows down almost every gold farm that uses magma blocks since they will now be able to spawn in them. Overtime, if you're afking at such gold farm the magma cubes will take up a large portion of the mob cap.

What I expected to happen was...:{}

They shouldn't be able to spawn when there's only 2 blocks in height,

What actually happened was...:

They spawn even though there's only 2 blocks in height.

Steps to Reproduce:
1. Build a huge magma block platform in a nether wastes biome.
2. Build a glass platform 2 blocks above it that completely covers it. (This should now in theory prevent ghasts and magma cubes from spawning. Ghasts do not spawn, but magma cubes do.)
3. Place a chain chommand block which kills Zombified Piglins and activate it.

4. Fly a decent bit above the farm and watch the magma cubes spawn. Since we are using a transparent block as top layer they will clip through it when they spawn.