Is there a way to remove unowned SKPhysicsNode in SKScene SpriteKit Swift?

Question

I'm developing a game in swift using SpriteKit. I create an empty Scene using SKScene(), then present it on SKView and enable showsNodeCount and showsPhysics. Then in the center of my scene appears a circle of physics object, which is <SKPhysicsBody> type:<Circle> representedObject:[(null)] with collisionBitMask set to 4294967295.

Screenshot of en empty scene

The debug node count states 1 node, but physics body node property is nil and scene's children array is empty. My guess is that it is a scene node.

IDK if related, but graphs and entities are empty too.

I set collisionBitMask to 0 at sceneDidLoad() using physicsWorld.body(at: .zero), but it get's a bit on my nerves, and looks a bit like a crutch. Is there a way to get rid of it, instead of changing collisionBitMask?