When vehicle blows up and spawns explosionsEffect shot (like FuelExplosion), it only uses instigator of vehicle killer for source instead of both source and instigator.
To summarize, when vehicle is killed by:
source=vehicle
instigator=unit
the explosion gets following parents:
source=unit
instigator=null
Repro mission hint you'll end up observing
Is this related to lack of vehicle or instigator on the entity in lastEntityCausingDamage @ T178711? I think it would be correct for entities to store both last damage vehicle and instigator and then use it for proper Killed event handler arguments and these explosions parents.
lastEntityCausingDamage is the engine pullup, so adding instigator would require the whole new implementation, not likely happening any time soon