As you see there is a similar copy / extract of points on a slightly different height level, ‘flying’ above the ground point cloud. Fair to say, that they disappear after some time. This is currently around the bridge here:
So a single 3D point is just created by pictures of one sequence but not verified / modified by others? Ok and all points are the sum of all points which explains the massive density by dublicate / close 3D points e.g. at street crossings. And yes of course this would explain this bug by bad heigth data and no fusion of the 3D datasets