3D text deformed while rotating

Hi i'm trying to make the 3d text but i got some problems.

I have a cube (resized as you can see in the video) and a 3d text that is instantiated at runtime and rotate towards the player (child of the cube). Now if the cube falls and i orbit around it i see the 3d text get deformed... how can i fix that ? any tips ? This is the link of my video: video