I have noticed the same in VLC Beta. It shows black bars instead in Kodi. I am not sure how it works in HDR but I thought Black (RGB: 000 000 000?) was Black nonetheless. Unless that’s a bug in the HDR algorithms in Sony Bravia TVs. Because I get that sort of dark gray appearing in some HDR dark night scenes as well. Sometime switching back to black when the camera in the scene switches position.