Golems have begun spawning outside normal boundary box for spawn. This has not happened in any previous version (not in 1.16.100 either).

To recreate:

Create a plateau above ground (far up from any other floors things may spawn on). Make the plateau out of glass to prevent spawning on the plateau. Place 20 beds on the plateau. Spawn in at least 10 villagers to claim beds, for golem spawning to happen.

Make a roof above villagers heads. The top of the block constructing the roof must be at a height 3 blocks above floor level (so villager can stand under roof blocks but cannot go on top of beds unless roof blocks are upper half-slabs.

Expected result: Golems will not spawn on the roof.

Result: Golems spawn on roof anyway.

Note: Cats and golems usually follow the same spawn conditions (except number of villagers needed). I have not seen cats spawn on roof.