Building a unique barn out of crimson wood, dirt, coarse dirt, water and shroomlights. After 3 calves suddenly disappeared, I investigated if it was the wood hurting them or finding a way to escape. Then I saw the calves going under the shroomlights, where they took damage. Did more testing to prove that it is the shroomlights.

Haven't tested if it's the same for other animals or baby animals, since where I tested is a desert survival world (lucky to even find cows). The grown up cows weren't affected by the shroomlights.

Did research on google and Minecraft Discord and found no details about it. Like to know if it's a bug or intentional feature.

UPDATE:

Realized after doing more research that calves take damage under any blocks. Was reported already, like report MC-47854