Quick answer: Unreal physics asset's default instance shared across all character instances? PhysicsAsset reference; instances modify the shared. Cloned at runtime.
Modify one character's physics asset; all characters change.
Clone per instance
Duplicate the physics asset at character spawn. Per-instance.
Or treat as read-only
Physics asset is shared; modifications via override at instance.
Audit physics asset mutations
Each mutation: shared or per-instance? Document.
“PhysicsAsset is a shared reference. Mutations are global.”
If you mutate physics assets at runtime, the per-instance clone is non-optional. Document.