mobs spawn in places that doesnt have blocks of air.

i was in a minecraft world in gamemode 3, and i found some mobs spawning in zones that doesnt have blocks of air, some of them spawns in bedrock. here a screenshot. it doesnt affect to the player. its hard to find that i was like 30 minutes trying to find more like this and i only found 5 mobs or something spawning in wrong places like this skeleton of the image.