The new iron golem/cat spawning mechanics in 1.17.30 make iron golems and cats unable to spawn at an otherwise spawnable X, Z location if there is any block above that spot up to Y + 6 of the village center. At the extreme, a spawn attempt can be blocked by a ceiling 12 blocks above where the spawn is attempted. This makes iron golems and cats unable to spawn in many underground villages and iron farms with ceilings/roofs above them.

Steps to reproduce

1. Load IG_cat collision check bug.mcworld. It contains two villages that meet the minimum conditions for iron golem spawning. Each village has command blocks that mark iron golem spawns within the village with a gold block and then teleport the golems into lava. Each village also has command blocks that can be used to toggle a stone roof at Y + 6 of the village center. The western village has a spawning platform that leaves 4 blocks of air under the stone roof where golems should be able to spawn. The eastern village has a spawning platform at the lowest possible Y-level where golems should be able to spawn.
2. Stand on the gold block between the villages and wait 5-10 minutes.
3. Go to each village and toggle the stone roof off.
4. Stand on the gold block between the villages and wait 5-10 minutes.

Expected results

Iron golem and cats spawn in both village in steps (2) and (4).

Actual results.

Iron golems and cats do not spawn in step (2). They do spawn in step (4).