Swets are impossible to spawnproof against, they spawn regardless of block light level

No matter how much the area is lit up, these guys will still spawn. I understand that the team wants them to spawn during the day, but having them spawn inside of fully lit up builds causes building in the aether to become a bit annoying pretty quickly.

Having them only ignore sky (natural) light rather than block light will allow them to spawn during the day, but not spawn anywhere someone has placed down light.

Zephyrs may have the same spawning issue, but I have not been able to thoroughly test.