Mobs are able to spawn on chorus flowers (regardless of their age). Doesn't make sense to me since chorus flowers are plants, are transparent blocks and don't occupy a full block (visually).
Mobs can spawn on top of azaleas and flowering azaleas
Zombified piglins are able to spawn on top of nether wart blocks
Mobs can spawn on scaffolding
Mobs are able to spawn on coral block
Mobs are able to spawn on melon, pumpkin and carved pumpkin