Hi Akhil,
Is the object on the floor part of your Unity scene prior to running the application on device? Pre-placing an object in this way can cause issues similar to what you’re experiencing. The tutorials are designed to first create a mesh and then instantiate objects onto viable mesh surfaces.
If that doesn’t help, could you try building in a more suitable environment? Reflective and shiny surfaces as shown in your video create discrepancies and inaccuracies with the mesh. If that’s not feasible, getting a wider scan area by moving around your current environment can help build the mesh properly.