Its not that its a bug. Its probably because the bounding boxes in some buildings are too small. Sure there must be a LOS system in place.
Is player in line of sight of explosion? NO>Take no damage. YES> Are they close enough to take damage? NO> Take no damage. YES> Deal damage, is damage enough to kill? NO> Deal appropriate damage. YES> Kill player.
Its pretty simple logic. Depends if it can be implemented well though.
Id be interested to know why exactly certain buildings are safe whereas others are not. Is it a wall/bounding box thickness issue? Or maybe its because the player character can clip through thinner walls meaning they are in fact in line of sight meaning they take damage? (I have seen bots shoot through walls because of this)
Well, I always saw things like explosives (esp. RPG/AT4 and artillery) as something to punish players who are not in hard cover.
It wouldn't be a big deal if artillery went through buildings though, so long as it was consistent.
Sometimes I'll be right next to a window, barely shielded from the shell exploding ten feet away, and nothing happens.
Sometimes I'm in a stairway, away from the walls, behind tons of hard cover, and get killed through a wall.
My personal take is that artillery should be something to force players to take cover or get punished, but that a player in hard cover should survive.
Maybe if the mechanic as implemented was better explained, and we knew what the "right kind" of cover and positioning was to survive it consistently, it would be OK.
But as it is, most of the time I'm just irritated that another random inescapable death has put me into spectate mode for 5 minutes