Try using position2d.global_position instead of just .position. Just saying position says its position relative to it's parents, so in this case, even if the player moves to the left, the position2D's position will remain (7.3, -0.8), because that's where it is relative to the player
global_position simply returns your position relative to the whole screen, which i think is what you want in this case.
Hope this clarifies things a bit for you!