Hi glitchyordis ,
Yep, that's the only needed line. Since depth inaccuracy is 2cm, this could also be a GT measurement issue as well, or a small rotation of the camera. Could you provide full recording (with lef/right), so we can cross-check ourselves?
Usually, for such plane measurement (table, metal plate), you'd also want to add pointcloud plane fitting and pointcloud rotation to eliminate the potential rotations of the camera (wrt the plane).