not sure if this is normal, when the wither is spawned inside bedrock, its explosions can go through the first block, hurting animals. When the first explosion (one happened when spawned) particles come out of bedrock and can hurt other things. wither skulls can also hurt other things through bedrock.
Linked issues
is duplicated by 6
MC-9509
tnt does damage through blocks it cant break
Resolved
MC-177161
TNT damage is transmitted through blast proof blocks
Resolved
MC-178440
Explosion (Creeper/TNT) destroy entity-blocks through resistant/indestructible obsctale
Resolved
MC-182690
Explosion effects entity outside bedrock box
Resolved
MC-194001
Beds killing in the end from any distance and behind anything
Resolved
1 more links
Attachments
Comments 2
Intended and can be read up here.
Notable:
Entities will always get at least 1 point of damage if they are within the radius, regardless of their explosion exposure.
When entities are away or covered by blocks from the explosion center, they take less damage.
Works as intended, I would think.