The Bug:

Rabbits will not spawn under a full block, transparent or not. They can fit in the space and other passive mobs will spawn such as foxes, however, despite not colliding with the above block will not spawn.

What I tested:

I tested this in a snowy_tiga biome at Y= -63 and also at Y= 80. I used snow blocks, and grass blocks for the spawning pad. and used glass, leaves, stone, and bottom trapdoors two blocks above the spawning pad leaving one air block in the middle. I also tested using top trapdoors instead of the air block gap and using medium amethyst buds facing down instead of air.

What Happened:

Rabbits spawned under only: the bottom trapdoors. The rabbits still spawn in the top trapdoors and in the amethyst.

What Should Happen:

Rabbits should spawn in all of the tested conditions listed.